when a direct deposit payroll debits the company account

It's actually not quite possible to tell.  In most cases they'll have their pay on Friday.

The ACH orders will be sent with a 'requested date' of Friday, but banks are free to put the money in the employees' accounts sooner if they feel like it, and sometimes banks might be late, especially smaller banks and credit unions - or when there is some sort of technical glitch somewhere along the way.

But, as an employer if you send on time and so the requested date is your pay date, then you've done your part.