Can a carb be tuned with an A/F gauge

They work well,Especially for a cruiser.I got the F.A.S.T Wideband setup to tune mine with, i was surprised at how off it was when cruising around and at WOT.After i dialed everything in, I think i picked up a couple of tenths and about 3 MPG.But like others have said everytime the weather or temp changes it'll be off some , I just change up the tune for summer and winter and call it good enough.