LOOKUP and Filter Based on Combined Condition

Here it is - with 5 sheets. If you want to try it with more, here are the instructions.

Copy Summary A6 & B6 down by ONE row.
Set calculation options to manual.
Click on day 1 tab name. Right click.
Move or copy/move to end (you may need to scroll down to see that)/create a copy.
Rename new sheet Day6.
In B2, amend references to A2 to correct row (a7 for day 6)
CTRL F3, edit the names of the 3 ranges that refer to Day 6 in line with the other ranges - the pattern is obvious.
Close
Summary last row in column B. Amend formula in 3 places to read Day6
Set calculation options to automatic.
Check that the slope/intercept are different from all others (I randomly excluded values all the way down the data).
Repeat as required.