I didn't use one at all during my entire PG or my homebirth. I had a beanbag i could put my chest on while on all fours to relax and i did a few cx with DP behind me and i put my head back on his shoulder and we swayed together.

I guess it depends on how you feel - if you feel you've used it a lot and had planned to use it, get a new one, if you just had it because it's what people have nowadays and you werent sure you'd use it (i'm sure they're great, i just didn't get one - might get one NOW actually! lol) then don't worry about it.

My true labour was under 4 hours, so i don't think my lack of fitball impeded anything.