Calculate hours that fall between a specific period for multiple shifts across a week

Hello,

I have a range of shift start / finish times (including DOW) for which I need to calcuate how many hours fall between 20:00 Saturdays and 06:00 Mondays. I have included the attachment showing an example of the data set. Range M7:M18 is what I am trying to fill, with the shift start times in K7:K18, shift end time in L7:L18, the start of the time period I want hours for in J2, the finish time in J3.

The base data for the shift start / finish times is in the format of e.g. 1/01/1900 4:20:00 a.m. for an 04:20 start time on a Saturday.

This has stumped me, so any suggestions / ideas would be gratefully received - I have many thousands of shifts to calulate so would rather not do it manually!

Many thanks