I do it overlapping. From the photos at SWCA, just from the way it's unfurling, it's clear (to me, anyway) how it was applied. The OCD question is just how long is the strip of tape?
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....And my OCD answer to that question is roughly 3-4 inches thereabouts. From photos of when it was "freshly" applied to the hilt, it looks to wrap tightly around the neck, so much so that it's impressed the ridge underneath into the tape. So I don't think it overlaps more than once. Also, from the way it's unfurling, it looks to unfurl from left to right. So that means if the hilt is laying down, emitter facing away from you, it would wrap counter-clockwise from the neck. I have mine wrapped with the ends facing towards the clamp because, in the photo of Luke catching it on the Sail Barge, I can't see the tape ends, either on top or under itself, so, it would stand to reason to me, along with the photos at SWCA, that the tape ends would face the "front" of the hilt, with the clamp and clampcard.
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I just use my fingernail.