Doing a 'down and welded' check in a fixed grear can lead to trouble in a retract. You train yourself, while flying the 'fixed', to chant "down & welded" and do nothing (there's nothing to do). This is setting you up to do the same in the retract!
However, if you know your aeroplane, how the extended gear affects the drag and perhaps the noise the aeroplane is making on final, then absence of such drag and noise will alert one that summat is not right. When I used ti fly the Yak 52 (no gear warning horn or auto-extend) I was always VERY aware how easy it would be to land gear up. One of our group members did so, after a go-around in a busy circuit.
Even religiously doing a 'gear down' check on short final isn't neccessarily a gauarantee..... If the pressure is on and the pilot is stressed it is still possible to do the check and still land gear-up. It's exactly what our fellow group member did!