I'm not sure about the time.It is written, that it can took many hours to check, but I think something went wrong, cuz 2 sticks took 1.5 hours and one by itself took more than 7 hours and still didn't give any results.
Using the Windows MEMORY DIAGNOSTIC tool, it took 2H38m on my defunct Pentium G645, 6GB RAM, test mix extended, cache on, pass count 5.
Hence I estimated 8 hours if I had chosen 15 passes (that's the maximum)...
I didn't check the time with the other tools.
In the past, it was possible to modify the passes on memtest86: over 4, like it is now.