I think Enterprise D treats the SickBay as a Mini Hospital given how many surgeries they perform. And there are extra SickBay's spread through out the ship in different parts staffed by different doctors that only a few ever get mentioned on screen. Since Beverly is the CMO, she probably only has to manage her fellow doctors and nurses and maybe take an occaisional shift.
My guess would be that the 'main' sickbay we see on the Ent-D is essentially the CMO's sickbay where the CMO primarily deals with the bridge crew, other senior staff, guests, diplomats and emergencies arising from command level missions (away team injuries or incoming emergency transports). The general medical needs of the crew are dealt with by larger but lower tier sickbays that we don't see. These deal with more regular care for the 'lower decks'. It occurs to me that these medical facilities could be staffed by civilian doctors rather than Starfleet Medical.
Enterprise "Blueprints" show a Much larger sick bay. They were limited by studio size for such a large room to be used sparingly. Another thing is that improvements in modern medicine have mitigated most of the long term care and recovered in a matter of hours or days. Think of the long term medical concerns that would normally require an ICU bed for days or weeks..... - Whalen getting shot in he gut (TNG: The big goodbye) - Picards Stabbing (TNG: Suddenly human) - 2nd degree burns (VOY: Deadlock)
You might want to keep the larger wing of the sickbay unoccupied and sterile, keeping a small suite for officers and minor scrapes…
Ultimately, you'd need a lot more medical staff than what we see - several doctors, several more nurses, a surgeon, a dentist, a pharmacist and a few EMTs (although this could be done on a part-time/voluntary basis by other crewmembers from other disciplines - I presume Starfleet training does include a First Aid course). I always imagined that the 'fourth wall' of sickbay expanded to what we saw on screen - that it has a proper hospital ward and facilities.
In an emergency, I'm sure large sections of the ship can be converted into temporary hospitals or triage centers. Otherwise, sickbay is sort of a clinic/E.R. that serves more as the CMO's immediate turf. Push come to shove, though, the Enterprise herself could probably become an impromptu hospital ship if necessary, IMO.
Keeping in mind too that TNG inherited the movie sets for Sickbay (and Engineering, the hallways, crew quarters, battle bridge, etc.) from the TOS movie sets, which were supposedly scaled for a smaller ship and crew of ~300-500 depending on the source. It's not much of an in-world excuse, but it does suggest that Starfleet picked a primary sickbay room size at some point and effectively standardized it across several decades. The same set was rebuilt for Voyager, double-dutied as the E-E sickbay once, and other sickbay sets (E-B, the Nemesis E-E, etc.) are roughly the same size anyway. The Cerritos sickbay seems both larger and more comprehensive, and we even see an inpatient recovery room. But, you know, animation... Mark
That's merely what we see of sickbay. We're talking about a television series. With live actors on physical sets, that have to be built, on soundstages of finite volume. LD and TAS are limited only by what can be drawn, and TrekLit by what can be described, which is why we've never seen Edoans/Triexians, Vendorians, or Lactrans that weren't animated, and we've never seen even animated Hamalki or Boquans. By way of analogy, consider the TOS sickbay. Now look it up on the Deck 7 sheet (sheet 8) of FJS's TOS Enterprise blueprint set. What we saw is at least duplicated on the other side of the deck, and duplicated in the secondary hull (Deck 16, on sheet 10), and there are "convalescent rooms" that we never saw, for patients who don't require as extensive monitoring. I think FJS also included a dedicated room for dentistry. (He also put Riley's bowling alley below the hangar deck, on Deck 21 [sheet 11], and I'd always postulated that it doubled as the Ship's Theatre, from "The Conscience of the King.")
We see Selar once, but she is name-checked frequently. But no way there weren't more doctors. Heck, the TOS Enterprise had McCoy and M'Benga.
The medical area which bodyswapped Kirk was held in during Turnabout Intruder surely counts as a private convalescent room - plus it was located down the other end of the corridor from Sickbay Doctor Sanchez gets a name check (by Dr M'Benga, no less!) in That Which Survives
Well, there is what we see what it is used for and then there is the rest of the facility that remained unseen. The series focuses on diagnostic, icu, and surgery. Same as TOS and TMP. In reality it is the same set built for TMP. It was expanded and altered to fit TNG. But it is clear that for a ship that large, what we see is likely only one of a set of facilities. There would be additional diagnostic and icu facilities and patient wards. But the stories never went there. It was always find out what is wrong and fix it. Quick in and out. Sternbach's deck plans have a far more extensive facility. According to him what we see is just a fraction. It is on deck 12.
Also, two things about sets already basically imply things beyond the walls: sudden unexplained alterations, and uses for multiple purposes. The TNG sickbay has both. Set changes are subtle, and since there is no major conflict between production order and airdate order, they don't go back and forth, so this is very different from TOS transporter room or engineering sets which really need to be interpreted as representing separate, parallel facilities in-universe, rather than alterations to single ones. Multi-use is blatant, though: in ST:GEN the sickbay set portrays a facility in the stardrive section, evacuated for separation, whereas the same set very much portrays a saucerside facility in other adventures. This doesn't need to affect our thinking much - but it defeats the contrarian argument that the sets would have been "intended" to portray only one thing, and all of that one thing. Timo Saloniemi
I was going to suggest my Forgotten Trek story, and then saw @bryce already did. Thank you Also check out "The Unseen Enterprise-D". It has a scan of the relevant deck plans from Rick Sternbach's Star Trek: The Next Generation U.S.S. Enterprise NCC-1701-D Blueprints. Andrew Probert made his own deck plan when he did those sketches for Star Trek: Online:
Ten Forward was converted into a triage center in "Disaster". I don't remember if we ever saw a cargo bay used for triage? But that would make more sense. I recall they're also supposed to have their own environmental controls?
If you have a cold or MRSA or whatever on the Enterprise, I'd bet you could just get infectious agents filtered out via transporter in like twenty seconds. Routine checkups could be done via handheld scanner whenever you had time. The Enterprise sickbay probably just had lot less to do in general no matter the size.
Here's a real life modern setup. https://ussgeraldrford.wordpress.com/2016/08/08/meet-the-gerald-r-ford-senior-medical-officer/