With regard to sheets creeping through the holes of an open net tramp, I have to say that in my experience this does not happen.

That is to say, assuming holes of 1-1/2 inch and ofcourse assuming through-going ("endless") sheets.
I have to add that I'm used to assemble all the spare of the mainsheet in my steering hand (I've big hands)on the tiller, while the other end of the sheet is in my other (sailing)hand.

The jibsheet I made so short that it will stay always onboard.

But I agree that it all depends on the habit of collecting the spare of the sheetrope in your hands. This habbit also make sense because it enables you to use the mainsheet traveller more often. So the lines to both cleats are tight and ready to be sheeted in or out.

There are by the way tricks for collecting and holding this sheet rest more easily in your steering hand.