It’s like that Supreme Court hustler case, but with turbulence
“I’ll know it when I see it”
Typically if it’s hard to adjust a heading bug, swap a freq, or write on my note pad it’s slow down time, or try a different altitude or course, if I’m having to make notable corrections on my controls to maintain course it’s VA time
But it’s all subjective to a degree, flying the work plane, what my company would call light to mod would make a delta crew secure their hats lol
In my own plane I’m seldom in a hurry and I unfortunately pay my own maintenance so I’m much faster to slow down or just land and get lunch