Testing OEM applications we check lash with a .0001" resolution dial indicator WHEN NEW. typically they'll have about .0003/4 NEW then they'll settle quickly another .0002 for a total of .0006ish WHEN the lash grows again THEY ARE ON THEIR WAY TO FAILING. Some may start out .0005 to .0006 and settle. We also check them via rolling as described here. The key is to check them new. We even have had an occasional lifter SETTLE about .0011" but again typically the 'wear-in' is typically about .0002" form as measured new.