I've seen mentioned here that too little lumens/hr can be compensated
for by increased photoperiod. Does anyone have personal experience with
this? I am wondering if there is a limit, do orchids need a "nighttime"
in order to bloom?

I've grown other non-orchid species that grow very well vegetatively
under 24 hr light, but need the light cut back to 12 hours per day in
order to flower.