trying to get 12 hour time format work hours/shift, with total per week with days off

I'm trying to set up an excel sheet with the workers in my department, for each day, including days off.

I want it to be able to show hours worked per shift (which can be a hidden column), as well as total hours worked per week. I don't want to have to use 24 hour time, as trying to convert the clockin/clock out hours to 24 hour time is annoying. I want to be able to just type in 6 in clock in, 9 in clock out, etc.

i have a little formula that sort of works, as long as you have hours for that shift. It doesn't work for shifts where there are no hours/off day. I'd like to be able to type something in those shifts (Off/Off or 0/0, etc) for easier reading - blank spots aren't so great.

Is there a way to get the total hours per shift to be formulated to count the hours if there are numbers, and just display "off" otherwise? I know how to make a sum formula to count up all the daily shift numbers, once I can get them to display properly.

The hours can change from week to week, which is why I want something in the daily total that can work for numbers or for a day with no hours.

Thanks!

I attached a copy of the one I'm working on at the moment. The formula is =SUM((12-B12)+C12), where B and C are clock in and clock out times repectively. It works for all numbers so far, just not with text....
schedule thing.xlsx

I was thinking something along the lines of having each daily shift totals (D, G, J, etc in my file) be formatted something like this: IF B#:C# (contains text), THEN 0, OTHERWISE (=SUM((12-B12)+C12)) etc, change for each day's block.

or something along that line. that way, days off where it says OFF will display the number 0 in the total, which can be calculated with the SUM function correctly.

Is something like this possible? I know you can format cells to be certain colors and such if there are certain values, im not sure how to apply it in this sense though, or if causing the cell to display something specific like that, with two different formulas trying to apply.

Thank you!

See if this works for you (attached).

Entry area is below "official" schedule and grouped. You can hide or display with Group functions.