The margin of the Enroute High sectional H-4 claims that the times of operation of the airspace R-5107K near El Paso are "1400-0300Z, MON-FRI" (and other times by NOTAM).
If the days of the week are Zulu time then by converting this to local time would yield "0800-2100, MON-THU".
You could argue against this interpretation because usually, we use the days of the week to reference the starting time, which would mean that the airspace is available starting at "1400Z MON-FRI" which is still "0800 MON-FRI" when converted to local.
But that doesn't explain that on the Enroute Low sectional L-5 the OUTLAW MOA is available "0100-0500Z, MON-FRI by NOTAM".
If the days of the week are ZUlu time, converting that starting time to local time would yield "1800-2200, SUN-THU".
Assuming the NOTAM for this airspace is active, do they really mean that the airspace is active "1800-2200, SUN-THU"? or do they mean that it is active "1800-2200, MON-FRI"?