OK I can come back to your 1st answer (145) with this ARRAY beast...
=AVERAGEIFS($H$16:$H$61,$A$16:$A$61,"will",$B$16:$B$61,">"&LARGE(IF($A$16:$A$61="will",$B$16:$B$61),1)-6-ROWS($E$1:E1),$B$16:$B$61,"<="&LARGE(IF($A$16:$A$61="will",$B$16:$B$61),1))
...confirmed by pressing CTRL+SHIFT+ENTER to activate the array, not just ENTER. You will know the array is active when you see curly braces { } appear around your formula. If you do not CTRL+SHIFT+ENTER you will get an error or a clearly incorrect answer.

But then if I drop the latest date (24 Nov), I get 159.8, or if I drop the earliest of 5 dates (20 Nov) I get 166.2, not 153