I have used a variety of flat methods including my own light box - but I always found that sky flats worked best as long as you have nice blue sky to work with.
So I ended up buying a fairly expensive flat box - only to realize that its nice illumination control was based on pulsing the lights rather than actually dimming them. That means that there are artifacts when using the flat box with my asi 1600 at short exposures.
This is a typical situation with artificial flats - they are too bright for cameras that have shutters and need long exposures - and they are too dim when used with narrow band filters.
And with progressive shutter cameras the short exposures don’t work because there is varying illumination across the sensor.
So - I haven’t used my expensive light box much with my asi1600 - and instead I use sky flats - and sit there with sgp manually figuring out the correct exposure for each filter - every time I take flats.
I find sky flats to be the best for a good flat that calibrates well - it costs nothing - and the only issue in taking them is getting the exposure right - which is relatively trivial to automate. It also involves no tracking and storing of “state” - i.e. the exposure needed in each filter. Every time you take flats you just figure out - at the time - what exposure you need for each filter - and you take them. If the lum exposure is 0.001s and you have a shutterless camera - no problem. If it’s 10s with Ha - no problem.
Anyway - I support the need for on the spot calculation of flat exposure times. You should just say - I need 15 flats each for Lum, Ha, Oiii - please take them now. And it would figure out the exposure needed at the moment for each filter and take them. Like I do now - manually.