Ive used this method ,and my mate still does.Nowadays I use a nylon lead with the clip cut off ,threaded through the collar,I have all the collars marked with my phone no in case a dog gets disorientated and lost.
Never had a problem with running a dog in a collar ,before anyone raises that issue,and it can be handy ,if you need to pull a dog off something quickly.
The toggle slips are too fiddly imo,especially when refastening them at night.
I have another one, a long leather lead with a collar a third of the way ,and a ring stitched to it the other end of the lead goes through it, the f