Chimonanthus retusus defoliating success.

[MichaelS]

This is after the second defoliation. It normally gets only 1 and the way it's going this year I might be able to sneak in a third. (I don't recommend this!!) Still no sign of flowers after 20 years. Probably because of the leaf cutting? One day I might just let it go and see what happens.
There are 2 magnificent examples in Murata's Four Seasons of Bonsai.

(That should read Chionanthus)

 

[0soyoung]

Probably because of the leaf cutting?

Probably.

Flowers are metamorphosed apical meristems. In some cases (like ume and 'bloom on old wood' species) these show up in strange places (i.e., axils along an old stem), but generally it means branch tips. Flower bud-set is most often determined by day-light time which is sensed by the leaves closely associated with the meristem.

So, maybe if you just keep the small cluster of leaves at the tip when you defoliate after the summer solstice ...
Or, treat it like ume if it is a species that blooms on old(er) wood ...