I really don't recall ever having a crash. In my Flavors of Subspace thread I do talk about immediate post session subspace and this flavor tends to be connected with a feeling of being tired (though not an intense lethargy) and more often than not I go to bed early. I do not consider that to be a "crash"

However I never did anything multi-day (it is rare that I do more than two hours)

I am going to raise one issue. I am going to make a guess that the 10 day period of unlocked chastity you posted about on Mistress Ayn's forum is the same as this one. I am going to quote your own words there:

"However, I believe that there is a lot of testosterone flowing as I spank it uncontrollably like a complete monkey-boy."

I am going to ask how many orgasms you had then. If it was a hat trick (or more) I think that might be playing a role in your crash