Yeah I didn't realise when I was making a new tactic from scratch i'd left marking to man, went into to the first game I couldn't even tell what formation I was meant to be playing because my players were all over the place.
I typically use Zonal for the whole team and only use Man/Specific for certain players if the formations don't match, say if you have 3 MCs (DMC+2MC ect) otherwise you might have 2 men on one, or a AMC marking a DC instead of a MC.