I use Dolphins too...
but I strip CAT5, and use them as a tiny crimp-cap.
I don't think the bed-of-nails spikes do to well with wire this thin, I think the insulation moves just enough sometimes to zig-zag between the piercing spikes and not make a solid bite.

Note, I crush Dolphins flat with the inner crotch of a set of diagonal cutters, but an installer of mine likes to use his crimpers which have slightly curved jaws and leave a tiny gap. I use that crimp method for butt splices and crimp caps (and I dont really use those anymore) but I was taught to use the diagonal cutters on dolphins.

Any feedback on which way is "proper" in your company??
Larry should have a definitive answer to post...