I have dishwasher powder so that I can scale down the quantity if I don't do a very full load.

I think trying to focus on the dishwasher being full does not work well if you do a lot of cooking, as you tend to produce a lot of dishes in batches, and then you don't have enough space to fit everything in & have to run the dishwasher with some stuff left on the bench waiting. Then you have to unload straight away to put the rest of the dishes away ,which then have to wait until you have more dishes and the whole process repeats. As long as it is at least half full I will run it to keep to a schedule that works for me.