I tested dma prescale value at power on time.
These percentages are not accurate, but a "feeling" of how often this happens. I need to count up and work out a real percentage for each.
About 90% of the time dma channel 0 prescale is 0.
About 70% of the time dma channel 1 prescale is 0.
About 30% of the time dma channel 2 prescale is 0.
Damn it's not a simple thing.