... thank God Lectraset (founded in London 1959) is in oblivion, never got single one that "took AND held"...
I really liked Letraset dry-transfers when they first came out for models. Mind you, to hold well, the sheet had to be
really fresh! It also helped that I had proper burnishers on hand. Although, even there, I found it helped to lightly 'pre-loosen' the transfer with a 4B pencil over a surface with 'give' before trying to apply it.
BTW, all my attempts with Letraset model stuff was on to flat enamels with no overspray to finish. Since I had other available sheets of Letraset meant for draughting and graphics work, I'd use them too. Again, good results ... except on gloss surfaces (they'd go on but didn't want to stay on). Overall, the standard sheets (and GeoType too) seemed somehow more 'forgiving' than Letraset's purpose-made hobby sheets
I've heard of modellers turning Letraset rub-ons into wet decals before applying them. Never got the point of that.