Sounds like you're making the maths of d2d more complicated than necessary.
Firstly 1/8th is impossible to do when we only deliver 6 days a week, and down here we only have 7 days in a week so not sure when you imagine that last 8th would get done!
Aim for a 6th(ish!). the ideal frame will have 4 rows and 6 columns typically having 20 calls in each column section.
This makes it easy, you'd do one column/4 sections or 80 calls a day.
If you had 7 columns do an extra section of 20 on 4 days, 8 columns add another section on 4 days.
Opt outs, Double or big slots, and business's will mean you will be doing slightly under some days or a few more on other days but I'd bet your loops don't all have the exact same number of calls either.