I'm kind of curious as well. It doesn't seem to mess me up too badly. Sometimes its just that it slips my mind and I get off by, as you say, around 1-4 days. Not longer. Sometimes its due to travel necessities like not wanting to cart all my ->-bleeped-<- with me for a 10 or less day trip. Sometimes I'm waiting for my refill to come in the mail.
I can't say i've noticed a mental/physical dip/lull/change really. Once I was out of refills and waiting on my doc to send in the okay, and that I had to wait for it to ship (though thats really only 1-2 days). Then I actually missed a whole week. Mostly what I had mentally I'm pretty sure was caused just from the anxiety of potentially opening myself up to the old curse and the what would probably worst cramps of all time. I do feel like my energy was also sort of down by the end of it. That, however, could have been all in my mind because I knew I hadn't had it, and it was over a year ago so its kind of hard to remember exactly how I felt.