Core memory diagnostics advice request

Greetings; I've finally gotten (again) my HP2100's to the point where I can run real diagnostics. The memory architecture doesn't appear all that different from a PDP-8E at the board level anyways (there's a memory controller board, a load board, an ID board, an XY driver board, and the core array). My question is this: I heard from a reseller that one should run the memory diagnostics in loop mode for 48 to 72 hours before assuming the memory subsystem is a good one. Bear in mind that when the diagnostic is run without loop mode, it only takes about 8 minutes to complete. This would mean 360 passes being made in 48 hours. From others experience, is 48 hours really necessary? I mean, isn't a good 4 hours enough to test for heat problems, etc? Unlike the reseller, I don't need to be 100% positive a board is perfect before sending it to a customer, I just want to be reasonably sure I can remove the memory system from the list of possible trouble spots as I go on to test other things. I was hoping that there would be nothing about the HP core subsystem that would require that long of burn in, and thus the experience others have had with other systems might be valid experience. So how long do YOU loop memory diags to test a core memory system to be reasonably sane? Thanks in advance! Jay West