Overtime formula not calculating a minimum set hours

Can you clarify how callout hours work, conceptually? My current understanding is that Regular hours are calculated using columns C through F, up to a total of 8 hours on weekdays. Overtime hours would be anything in excess of 8 hours in columns C through F on weekdays. Callout hours appear to be all weekend hours and anything from G through J on weekdays. I'm of the impression that if a worker works at all on a weekend or after 16:00 on a weekday, then he/she is entitled to at least 3 callout hours for that appearance, or more than that if he/she works longer than 3 hours. I don't understand where the 27.50 value in M4 comes from. Is that the error we're trying to fix? Should that value be 3? Something else?

Please confirm or correct my suppositions so I can be sure that I'm not making things worse...

EDIT: Looking more closely at your formulas, I think I get it now? If someone is called out at all in a callout period, he or she gets at least 3 hours for that period. So if I'm called out for half an hour during each of the four weekend periods, I would qualify for 12 callout hours, correct? If so, try the following:

Weekdays (enter in M4 - returns 6): =IF(G4="",0,MAX(3,(H4-G4)))+IF(I4="",0,MAX(3,(J4-I4)))

Weekends (enter in M3 - returns 9): =IF(C3="",0,MAX(3,(D3-C3)))+IF(E3="",0,MAX(3,(F3-E3)))+IF(G3="",0,MAX(3,(H3-G3)))+IF(I3="",0,MAX(3,(J3-I3)))

The IF clauses in your formula include some odd clauses "(I3>J3)*24)" that I don't understand. If your time data is entered correctly, I3 is never greater than J3, so this addition to the clause returns 0 (i.e. 'FALSE' * 24. Otherwise, it returns 24 (i.e. TRUE * 24). I'm not sure of your intention here, but it seems unnecessary.