One thing Star Trek has often not done is get the fleet sizes believable, especially the Federation's. This is tied into distance and speed problems.
Just 12 heavy cruisers? No way.
You're going to set up a blockade of a few dozen starships in a concentrated area like a solar system (e.g., Wolf 359)? LULZ, NOPE. If we can outrun your fastest ship (which we can, resistance is futile), we'll just warp right around your whole fleet, have dropped our assimilation bomb on Earth, and be gone before you've even gotten there!
Star Trek has always been bad at establishing a consistent scale. Discovery probably being the worst (since they gave hard numbers a bit more than others), but I know Voyager did it a lot too. And yeah, TNG and TOS with fleet size.