can i just do the very last fort condor mission in order to get the huge materia and pheonix materia or do i have to do all 17?

you can just do the last one

and you can't even do all 17 since *spoiler spoiler* happens

but since it's so fun, you should just do as many as you can

you should do them all regardless since you get free items for completing it.

Only items you get are a triple growth materia wep for yuffie and exlixer/xpotions/etc

For the amount of back tracking and ease of missing the times to do all of these, it is not worth it at all.

Man I forgot all about fort condor. This minigame was so fun.

i forgot all about all the minigames in final fantasy 7. I wanna go play it again now