Assuming this byte only represents the user selected time for a circuit, i.e. It is not the actual running time, as that must consider the user set program percentage and possible other factors.
Here are variations on option 3:
A. With minutes and hours; This would allow the user to set a circuit to run as long as 196 hours and 59 minutes, in 1 minute increments.
B. With 30 seconds and hours; This would allow the user to set a circuit to run as long as 136 hours and 59 minutes and 30 seconds, in 30 second increments.
C. With 15 seconds and hours; This would allow the user to set a circuit to run as long as 16 hours and 59 minutes and 45 seconds, in 15 second increments.
For my uses, the 1 minute increment is the best choice. This is because it would be the easiest to set, while not limiting the running time.