The majority of airlines I work with don't require a head count, and the one's that do often take two or three attempts to get the head count right... Therefore I see the whole practise of counting heads fairly pointless.
750XL, am amazed to hear that - thought headcount was a standard practice.
The fact that it occasionally takes an extra count is, in my opinion, not a valid reason for not conducting same. It's a procedure which is the last line of defence.
The last Company I flew with for several years was a loco where we did 25 minute turnrounds and the cabin crew were
always required to do a headcount - if there was a discrepancy it was sorted before departure.