LOL,

you'll all right and wrong.

It's best to download anything you find interesting then try it for yourself. Trust me you'll get bored of trying that 20th compressor and download less of them.

Now i've done the donkey work and tried everything I now use around 20 plugins for everything. For example I only use nexus, massive and sylenth. I know these synths inside out so can make any sounds I need quickly! I can always replace them with better at the mixing stage for example trupianos usually replaces the nexus built in pianos.

Effects wise I use only a few also.

For limiting elephant.
for compression, ableton's own or waves
for distortion, ableton's own or ohmicide
for reverb, breverb or ableton's own
for delay, abletons own or dubstation
for glitches stutter edit or effectrix

I use some others like gclip or rdesser but very little else is needed for most tracks unless it's needed.

For vocals i like to use melodyne standalone to really manually tune the shit out of a vocal session.

It never really comes down to disk space but more down to bogging down a system especially a laptop. If you have 600+ plugins it's not gonna be as easy to work with just the few plugins you really like instead you'll be hunting. Also when opening old projects you might have issues with plugs you uninstalled or don't have on a different system.

Keep it simple and you'll be rewarded in the future. Also you'll more realistically be able to purchase and support the plugins when you start to make some real cash from it.