You can prolong the life of 3rd gear by installing an aftermarket shifter that has a hard stop for the shift lever.
I have been road racing the T-5 in my Mustang since 1993. I don't beat on it, but I can't say that its life has been easy, either. I use
synthetic ATF in it and have had no problems after all these years.
I think most who have problems are abusing it by drag racing or power shifting. Just my .02.