1/2” on tops and 1/4 on sides and backs but that’s just me

ok I done some seats with 1/2 on sides but I feel they are to bulky when doing double top stitch... I'll try the 1/4

I often debate this myself. I either use 1/4 or nothing. It’s the seat style for me that makes me choose. I never know if it’s needed though. Oil style spring seats where there’s no foam from the cushion behind it I tend to add sew foam more often, vs the newer seats.but again I have no idea

10mm on seat faces if they're top stitched (pleats, diamonds, etc), 6mm bolster faces, 3mm for sides(normally only for backs not bases).