Count the number of full weekends worked (Sat&Sun) in an excel shift-work roster for each staff member over the current calendar year - excel-formula

Question

I have an Excel rostering spreadsheet for shift workers and need to count the number of full weekends rostered (Sat&Sun) on/off for each staff member over the current calendar year.
I have tried several formulae, tried named ranges, countif, countifs etc. but am having problems counting identical values in two consecutive columns (days) in the same row i.e. Saturday and Sunday. Single day counts (such as number of Sundays worked) is no problem but I'm stumped with how to calculate the number of weekends when both days are rest-days, for example
The following works well for the number of single Rest Days (RD) falling on a Sunday but I need to determine the number of weekends in which both days(sat & Sun) are Rest Days.
=SUM(COUNTIFS(ROSTER!$M$17:$PM$17,"Sun",ROSTER!M28:PM28,{"RD"}))
The above is a small sample taken from a worksheet that contains a complete year's roster. Each roster is a two week block,starting on Sunday, with a column titled "RDFN" between the Sat and Sun at the end and beginning of the next fortnight.

Answer 1

Edit 2
As confirmed you want to count the number of weekends where both Sat and Sun are RD (Rest Day) in a given time frame.
I have revised my SUMPRODUCT formula (which works as COUNTIF in this case) to find the result for Jane. Simply drag it down to apply to other employees:
=SUMPRODUCT(((B5:AH5&C5:AI5)="RDRD")*((B$2:AH$2&C$2:AI$2)="SatSun"))+SUMPRODUCT(((B5:AH5&E5:AK5)="RDRD")*((B$2:AH$2&E$2:AK$2)="SatSun"))
This formula is using two SUMPRODUCT formula and adding the results from the two. Both SUMPRODUCT formula followed the same logic.
It will work in the case you have two columns between each fortnight, and it is actually slightly shorter than my previous
solution.
Let's take Jane's data for example. Imagine you have inserted four helper rows.
The formulas in the first helper row are B$2&C$2, C$2&D$2, and so on so forth till AF2&AG2, which represents SunMon, MonTue, TueWed, etc.
The formulas in the second helper row are B5&C5, C5&D5, and so on so forth till AF5&AG5, which represents RD8 M, 8 M14 A, 14 A14 A, etc.
So the first SUMPRODUCT formula is counting the number of RDRD in the second helper row when the corresponding position in the first helper row is returning SatSun.
First Part =SUMPRODUCT(((B5:AH5&C5:AI5)="RDRD")*((B$2:AH$2&C$2:AI$2)="SatSun"))
However the above formula is not working in situation where the last Sat of the first fortnight and the first Sun of the following fortnight are both RD because there are two columns in between which will not return RDRD in the second helper row so the match will fail.
To overcome the problem, I have to use a second SUMPRODUCT formula with the help from another two imaginary helper rows.
The formulas in the third helper row are B$2&E$2, C$2&F$2, and so on so forth till AF$2&AI$2, which represents SunWed, MonThu, TueFri, etc.
The formulas in the forth helper row are B5&E5, C5&F5, and so on so forth till AF5&AI5, which represents RD14 A, 8 M9 M, 14 A6 M, etc.
The second SUMPRODUCT formula is also counting RDRD in the forth helper row when the corresponding position in the third helper row is returning SatSun.
Second Part =SUMPRODUCT(((B5:AH5&E5:AK5)="RDRD")*((B$2:AH$2&E$2:AK$2)="SatSun"))
Adding the results from both parts will give you the total number of weekends where both Sat and Sun are RD as shown below: