Violentlash, my latest fortress which has run for 35 years now and I'm thinking about finally retiring, has started with 42 dwarves through migration and had a max population of 135 through births (yes, this means at an early point I had 80+ children/babies around...). I found this number of dwarves and the rather slow way of how they became new working force really good and it allowed me to focus on who can do what, going by personalities etc., if I needed it.
I have 38 (previously 39) military dwarves, 12 of them marksdwarves, 26 (prev. 27, one died of old age) melee. A decent size, I would say. Could use a few more marksdwarves. They are on constant active duty, either training, being stationed at the entrance or fighting.
Jobs all have 2 to 4 dwarves assigned to them, perfectionists do the quality related professions and have several professions enabled while non-quality related professions just have 2-4 dwarves focus on them. I have 4 designated miners, 2 carpenters (who are also bowyers, but I never made wood/bone crossbows), 1 designated woodcutter as well as 2 who also have other professions. I have no need for Masons, instead focussing on Green Glass production via a Magma Glass Furnace. 3 perfectionists are engravers but they also do other professions, these dwarves for example are also glassmakers or weapon/armor/etc-smiths.
3 (prev. 4, one died of old age) are animal trainers. 4 are doctors. They all do nothing else, not even hauling, with the exception of one of the animal trainers also being a butcher and gelder - these less used professions don't really matter.
Then I have a few planters who are also herbalists - not that I need herbalists though, but I like having different plants available. 2 designated dyers, considering the production of cloth I got going on, I need them. 3 who make soap/are woodbuners/potash/lyemakers. 2 cooks, 2 brewers, a few who are threshers, millers, ... I could actually give these professions to one dwarf or two each, but from before I still have a few dwarves who have multiple of these professions enabled at the same time, because they aren't used that often. I have 2 beekeepers who are also pressers since I have quite a sizeable beekeeping industry (I modded bee-related products to be more valuable). No fishers anymore, quite a few furnace operators. Most smiths also do other professions because I picked the best for these quality related jobs. 1 gem cutter/setter. A few designated leatherworkers and clothiers...the rest of the professions is taken up by some dwarves. It's all a bit mixed for whatever jobs aren't required that often.
And then I got 31 dwarves who pretty much do nothing but hauling. I marked them by them being the only ones who have pump operation active. The other non-critical dwarves also got hauling active. I currently only have 3 children/babies left, leaving me with a very good hauling force. If the game would assign jobs properly and quickly still, I could remove the remains of a goblin siege in a very short time for example - sadly more than half the dwarves sit around with "No Job" for an eternity before the game decides to assign the hauling/dumping jobs again. It always happens in waves until a few items are left which then don't get picked up for quite some time...
Anyway. The more dwarves you have the more you can assign one (or better two) dwarf(/ves) per profession while still keeping a massive hauling force and sizeable military.
Then again, I turtled up early until my military was combat ready, the first siege arriving at 50 dwarves (8 births had to happen). I fought off my first siege a few years later, until then I just let them wander outside with the "doors" (bridges) closed. If you have more loss you will need to replenish those casualties as pointed out of course.
There are a lot of professions, so use a lot of dwarves for them, I say. But the main need for that work force will always be the military and hauling. Keep the critical professions manned with a few non-hauler dwarves who are then always safe in the belly of your fortress.