Hi Herman,
I think, at least on the hardier species, whether you get a leaf or flower must be predetermined at the time of dormancy, mainly by the size or possibly somewhat by the age of the tuber on smaller species.

Damaging the largest or apical bud seems to always wake up the sleeping ones, but then there is often a long delay for them to get started again and it throws them off schedule to grow outside in the ground here.

Keiko