I use the clips and get on fine with them. Not hit and miss. If you are getting into a sticky mess then I suggest you are using too much gel in the PopIt. The gel really shouldn't seep .. But you need a nice light touch when applying the PopIt. It is important too, that the clips you use do not clamp the PopIt to tightly to the nail and cause the gel to seep.
I do one or two nails at a time and cure for one minute using the clips and then remove the PopIts. When I have completed all ten fingers, then I cure the whole hand or five fingers at once again in my CND UV lamp for a further two minutes to make certain of a complete cure. No need to apply a finishing gloss at the end, which saves more minutes off the service time.