Number of employees on schedule per hour

Hello

I am new to this site as I usually am able to figure these things out on my own but desperately need some help now.

So what I am looking to do is bucket the number of employees that I have working on staff at every given 15 minute increment according to their repsonsibility #

So if I have two employees that have the 2 responsbility working at 5:15 then that number would be 2.

This seems pretty simplistic on the surface but the issue that I am having is that my store is a 24 hour operation so I have employees on staff from 10 pm to 6 am and it confuses my countifs formula.

I have attached my spreadsheet for reference.

Any help would be much appreciated.

Thanks in advance.