Yep, it really comes down to wing loading and to some extent the airfoil selection.

There's funfly semi scale GeeBees that fly slowly super great and Extras that came out way to heavy and have some building errors in the wing that make it an accident waiting to happen.

I've flown a very badly designed Cub that was a violent snap roll into a flat spin model. It wasn't even that heavy but it WAS slightly semi scale and probably had a very bad airfoil. It only flew 3 flights before it entered a spin at a height below that required to tuck and then pull up.

So it's not the basic shape but a lot of factors all put together..... and it can be a big list at times.