Man of Honour
As someone who did their first 15s only a couple of months ago and is doing them again now, I see what you're saying and yeah 15s do take it out of you. I don't think not being conditioned for 15s would account for that big a difference however, so it jumps out to me as a red flag for other problems, my first guess being form. If it was only a 15% of 1RM increase instead of the 10% increase you'd expect from then yeah I'd say it's not important, but it's quite wildly different. A 15RM of 60KG would make your estimated 1RM 92.5KG - so a 100KG 1RM would be pushing the limits - whereas a 10RM of 90KG puts the estimated 1RM at 120KG! Makes me wonder what the guesstimated 5RMs are.
Yeah I'll stop obsessing over it now
Yeah I'll stop obsessing over it now