You will find using several 1/2 hitches on smaller gauges not an issue.. Heavy trace, maybe and this has only varying degree of support.
The main issue that causes 1/2 hitches to loosen is how tight the line is pulled upand tied behind it.
Its the same with tightening shoes laces, which is basically 2 1/2 hitches.
A the lace comes undone from below the knot because the laces have not been pulled up enough to keep tension on the bottom knot...even if the lace knot has the 'double' put on at last.
That used to be the very 1st 'lesson' of the season to parents (and players) when used to coach junior football.
The only time I ever had 1/2 hitches loosen enough for the main line to fail was way way back when tended to be a bit lazy in discipline pulling up turns as go.
And that is most likey why ppl have issues with knot going loose.
In saying that, I I tie a surgeons, clinch, and numerous other knots, I put a 3x rizzuto on the back of it.
Maybe over kill, but there have been the odd occasions when cut the tag back flat, then had the tag tip pull back thru.
So it just a little 'insurance' where having a slim knot is required for casting smooth thru guides... and finishing a bimmni or a FG with a rizzuo, tends to bunch rather than lay the twists flat.