Are you sitting comfortably children? Then I'll begin...
Back in the day (let's say the early 80s) I would fit my strap to my guitar each time I played and remove it afterwards. Before too long the leather around the slotted holes became fatigued and all chewed up, to the point where it could not be relied on to stay put. After a few near-misses I would reluctantly toddle off and buy a new strap, although I kept the old one 'just in case'.
Once I started gigging regularly (90s) I decided I needed something more reliable. As I usually took 2 guitars (not basses) to a gig, I purchased 2 sets of plastic doodads and fitted them to a couple of straps. I can't find a picture on Google, but they were terrible. The bit that enclosed the existing strap button was ok, but they were secured to the strap with the worst fittings ever - the screw heads had wide, shallow slots, with which no screwdriver bit known to man would engage.
Eventually I gave up and started fitting Schallers. I still have these on most of my skinny-string guitars, but they are not without their problems, namely:
(1) There is no way to lock the large nut to the strap, so it tends to come loose;
(2) I have had the whole thing come apart, with pins and springs rolling round the stage;
(3) They can creak as you move the instrument around;
(4) If you have an instrument designed to be stood on 2 strap buttons, the strap lock doesn't allow this; and
(5) The arrangement puts a greater torque on the screws that secure the strap-lock buttons.
On my basses I have now gone over to Grolsch washers. I have a Neotech Mega strap 'permanently' attached to each of my Precisions, and a Comfort Strapp on my Mustang. It's a relatively costly solution, but the most secure as far as I can see. Arguably I could dispense with the washers as the slotted holes are not getting stretched over the strap button flanges, but hey-ho.
I have also tried the black plastic disc-type locks. They are generally fine if you have 3 hands (1 to hold the guitar, 1 to hold each part of the lock) but it seems to take excessive force to remove them from some strap buttons.
If there is a moral to this story, it is only that there is no single perfect solution. Also it is surprising how much boring guff I can type when the mood takes me