Sum Percent Complete Based on Filled in Dates

I'll try my best to explain my problem.

I need to have Excel read if a date or the value "not required" is placed in a cell, and based on that, sum them to form a percentage. The issue I'm running into is this needs to be applied to four cells, however they are not in a range, they are scattered (ex. S1,W1,AA1,AE1).

So essentially, I need it to look at these four cells, see if they have a completion date in them or the value "not required", and then assign a percentage. So if two have a date and one has the value "not required" the output cell should read 75%.

New poster so if I broke forum rules, my apologies.

Regards.

Will there be anything in those cells other than a date that should be counted, or "Not required"?

If those are the only possible entries then a simple =COUNTA(S1,W1,AA1,AE1)*25% should suffice.

That seems to do the trick, some other cells have requirements where that won't work as well but I think I have enough now to make the modifications to get everything up and running, thank you very much.