I used spacking to fill a hole that is like really wide, but not that lengthy. I painted it, then put more spacking on the hole. The hole is still noticeable. So like if I just keep putting more spacking, will it sooner or later look noramlish?
Muralo's Spackle™ shrinks as it dries. If you keep applying thin layers and letting them dry, you will eventually achieve a flat surface. If the Spackle is proud of the surrounding surface you should be able to sand it flat.