Personnaly, I don't find it's time consuming.
I sometimes stamp the piece when the work is done and it's still hot, I take one last heat and "Bam", Done.
Other times, I heat with the torch only where I will be stamping, and "Pow", Done.
I had a client that baught me a dragon chandellier (in a craft fair) that I had made before I had my stamp.After paying me, asked if I could sign it and he would pick it up at my house. That was a 50 miles detour for him.I thaught it was quite flattering.
Naz