Got a Zesty with a Fox float rear shock on. Had to replace the lower shock eyelet bush after about 5 months, which I thought was a bit soo, but all was fine however its knocking and started developing play again after only about 8-10 rides !! Is this normal ? OK all the rides have been in the real grotty conditions of mid winter, but its going to be a real pain if I keep getting through them at this rate ! Does this sound like normal wear rate. (its only the lower end that needs doing each time), does the weather and wet conditions accelerate the wear on these eyelets ? Is there anything I am doing wrong ? I heard a rumour that Muc-off is not that kind to them, but I dont know if this is just an old wives tale ?

Have you replaced both the bush and the eyelet insert or just the bush?

Depends on your riding, a mate of mine goes through bushes on his Commencal Meta 5 at an alarming rate. Another mate used to go through quite a lot on his RM Slayer Sxc where as I on the same bike didn't. When I changed mine I swapped the normal Fox ones for a BETD needle roller bush which is lovely and is lasting a lot longer then the normal fox one. Drop them an email to check they will fit-I think they will be ok for yours.
Not heard the muc-off thing myself.

Have you replaced both the bush and the eyelet insert or just the bush?

Just the eyelet

Change both everytime to be on the safe side. A 'steel pin' (tube with spacers on either side) is a good bet if your worried about bushes wearing quick.
BETD and some other do them, or the needle rollers but haven't used them myself.