Star Trek: U.S.S. Enterprise Haynes Manual (yes I know) mentions 16 holodecks.
If I lived on a starship without seeing the surface of a planet for several months and the only other options of entertainment were the poetry of Data or the plays of Dr Crusher, I
could kill for some hours in the holodeck...
Edit. If you accept the number of 16 holodecks and that at any given moment there are ~670 people in their free time, you can satisfy the holo-needs of only 2.4 % of aforementioned people.
I'm surprised that aren't lines outside of holodecks...
Who says there aren't other forms of entertainment on the Enterprise? on contrary there seems to be sporting facilities (like the one Picard and Jono played that weird squahs-like game in Suddenly Human) the arboretum (which seems to be large enough to allow Riker and random female crewmember to fool around in without being disturbed) I think the pilot mentions some sort of swimming pool.
There is some sort of private holograms you can watch in your quarters (Riker does so in Haven, despite all the insistence later that television is dead and gone) the ship computer offers free and unlimited access to the literature, media and trivia of countless civilizations (imagine that wiki walk) I assume there are classes like in community centres, the Ten Forward exists, people meet for card and board games and apparently some sort of virtual game also still exists. It's not like there's only the holodeck.
What is unrealistic is that there's always a holodeck available when the main characters need one.
Though perhaps using the holodeck extensively and on your own in a little bit frowned upon, because it carries the stigma of getting addicted to it, like Barclay?