Well, for many of the film years I had just 3 lenses. 28-85, 50mm, 80-200. As I went digital still kind of had the same with a 24-85 which I switched up to a 28-135 IS, 100-300mm and 50mm. Then all heck broke loose and I jumped to L's with a 17-40, 24-105 IS, and 70-200 IS all f/4L and Sigma 85mm f/1.4.
Then I added a 50mm f/1.4 Sigma to these and thought OK, lets add one prime in the middle of each so I also added the 135L, swapped the two Sigma primes for their bigger L brothers (always buying used). Then someone showed me a f/2.8 24-70 and 70-200 IS so I sold all the f/4 and got f/2.8 versions. Now Im not sure I would do this again since I think the f/4 set is a great set to own and would recommend it to anyone and when i think of owning primes and zooms I still think this is a very good pairing. Lighter, flexible zooms, and fast primes of 35, 85, 135.
My zooms are primarily for sports, soccer, rugby lacrosse, basketball, football, etc. So today I used just two zooms while taking pictures at a Rugby tourney, 70-200 and 70-200 with 1.4x on my 1D Mark IV for on field play and 24-105 on my 5D Mark III for the players around the sidelines and when they were up
close to me.
I also love portraits so I use the 85 and 135 get used for that. The 14, 24 are for the landscapes. As I mentioned I plan the sell the 24L since I prefere the TSE-24L II for landscapes over the normal 24L
The 35 and/or 50 are for night shots walking around. For me the 24 is too wide on my FF for that but I know a lot of people love it.
Other lenses have shown up for specailty work or since I buy used 80% of the time its because I found a good deal, too good to pass up, and thought I would try it. Or its from an earlier line-up I just haven
t had the time to sell yet. The 200mm f/2.8 is like that. I bought it, because it was a great deal, to use with my 70-200mm f/4L to have a f/2.8, together they were cheaper than any of the 2.8L 70-200mm.
But as I said I eventually traded up to the 70-200mm f/2.8L II which pretty much performs as well at 200mm so I really should sell it off but having a long black lens sometimes does have its uses.
Primes vs. Zooms, I believe they both have their uses so I own both. The zooms are primarily for sports or events like graduations and weddings. The primes, when I have a little more time to think and compose or when shallow DOF are a must have or at night.