Set PSC_ACCZ_P to MOT_THST_HOVER is out of range!

i have a question about PSC_ACCZ_I and PSC_ACCZ_P
is setting these parameters are necessary ?

what will happen if i don’t set them ?

and nother question is that my MOT_THST_HOVER is 0.26 and when i want to set PSC_ACCZ_P to 0.26 mission planner show a warning about out of range value
i checked docs it seems that minimum value is 0.5 should i ignore this warning ?

yes, you can ignore this warning

What does it say here?
Initial Tune