Caluclating time issue

Ok I've been working on my time schedule for work and I've been using this formula:

=MOD(TEXT(RIGHT(A1,4),"00\:00")-TEXT(LEFT(A1,4),"00\:00"),1)*24

to calculate the number of hours. This formula works great as long as the time period is in one cell, Example (0600-1400).
My problem is that my third shift works from 2200-0600. On the schedule I can't put the time in as 2200-0600 in one cell, it has to be like this:
First Cell = 2200-2400, Second Cell = 0000-0600 2200-2400, Third Cell = 0000-0600 2200-2400, and so on, and so on until their weekend.

Is there a formaula to calculate two time periods in the same cell like above or is there a formula that can handle both, for example lets says
like a first shift person needs to be moved to third shift for a night?

not a very good way of calculating time, excel has a built in time calculator, but it must be in the hh:mm format ie 9:00 = 9:00 am and 13:00 = 1:00 pm, excel can figure this out so you should have clock in and clock out times separate columns so you would need 6 columns three for clock in and 3 for clock out then you can just add and subtract to get hours per shift