Overlapping Time Intervals - Formula to Show Start Overlaps

Good morning,

I have previously posted a question in regarding time interval overlaps. https://www.excelforum.com/excel-gen...ml#post4763725 (Thank you 63falcondude!)

I have a followup question regarding the same data. I have a limited amount of spaces to book, but many "classes". What I would like to create is a formula that can show me how many courses are in session at the start time of each course, so I can tell if I can "recycle" a space.

Attached below is an example of what I would ideally have the spreadsheet appear like, with the "courses in session at start" the summary tab that will show how many rooms are filled at the designed start time for that row. I would need the information compiled much like in the way that Row P is now. For example, P7 (highlighted in orange) shows that the 4:50-6:50 courses have been released, freeing up the space it occupied, which can be re-used for the 7:00 classes.