Counting the number of working staff during specific time periods

Jen_Sova It worked.  I created a simple LAMBDA function called Toffset that will +1 any time < 7am or whatever time you pick.  I then used a formula 

SUMPRODUCT( (Toffset(start_range) <= Toffset(Start_time) ) * (Toffset(end_range) >= Toffset(End_time) ) )

I used $ to  'lock' columns/rows as needed so I could easily copy down and across

I also added 9/24 to the Toffset for the END times so any end time like 7:30 was also interpreted as the next day also (i.e. up to 9am)

I added a FILTER at the bottom just to 'copy' the values above so I could more easily do a manual check

I started to highlight the correct outputs green and wrong red but after 2 days stopped as it looks like my formula is working.

Let me know if you have more questions.

BTW I changed to SUMPRODUCTS because that will handle an array while COUNTIFS requires a cell range.