It's nothing to do with days really worked or wages paid for. It's directly relevant/proportionate to amount of wages/salary paid or payable to the employee for every month. This would apply to/on leave salary payable as well. Even if he/she worked for one day PF has to be deducted thereon. While saying so, if he/she is on LWP for which no salary is payable there is '0' to PF a/c.