I think the main point about full flaps is that these are drag flaps rather than lift flaps. Consequently you do not select full flaps until you are certain of reaching the runway, and you can only judge this on final. Once full flaps are extended, you are committed to land. The same principle applies to both powered and glide approaches.
The point at which you select full flaps does not have to bear a relationship to the height AGL of the aircraft. Nor does it affect a go-around because you will be retracting flaps for that anyway (subject to what your POH says). Twins are different but I presume we are discussing singles here.