Im in my 30s and use one daily. I dislike having to tie laces every day and i can slip my feet into my shoes (while perma-tied) like butter.
Yes the laces are slightly looser than a fresh re-tie but not uncomfortably so or slopping around when i walk.

I wear faily flexible everyday shoes though, would not reccomend this technique with rigid leather dress shoes or work boots which need to be tied every time.