I've made a few jigs for the table saw that needed runners. What I found was that my runners were just perfect before I attached them to the jig but after I screwed them on, the screw seems to widen the runners just a tiny bit so that they don't run as smooth. This requires extra work to get them running perfectly again.
I notice people on YouTube gluing and then screwing their runners. I don't see why you'd need to screw them if the glue is doing all the work (considering that on most sleds the runners are not under stress).
I've also noticed that solid wood runners don't show this problem as much as UHMW (ultra high molecular weight polyurethane) ones. I've never tried metal or plywood runners.
Note: I always pre-drill my screw holes.
Has anyone found any problems with just gluing the runners?