I used to chop and change between flats and clipless on different bikes, then rode just clipless for a few years, it was only when I started riding steep off-camber jank in the wet and found myself unclipping in anticipation of needing to unclip, that I decided flats were for me.
It was actually a faster mate who pointed it out while following me riding down a trail like a Gumby and yelling at me to stop unclipping.
As well as having some dumb low speed stacks, one of which cost me a CSU as I got hung up in a techy rock climb and couldn't unclip...
Once on flats I found the foot doesn't leave the pedal as I know it will come off at anytime if I actually need it to. Mind games ey.
Also riding motocross a lot over the years means hanging the foot out when leaning over is natural to do at times.
Still ride like a Gumby though...