WHYYYYY???

I presume the "why" is a rhetorical question? There is no good answer (that I know of).

  It's just the human condition.....

Are you saying you have always experienced them in high numbers or is this a new phenomena?

The answer is as follows horny men can be pathetic, and in sexual frustration, often rub one out themselves by accident right before a date, therby killing their carnal mood. They know they messed up and can't present themselves.  This happens a lot. Or, on the converse, they hit up multiple ladies at once to secure a date, knowing they will dump all but 1.

As a hobbyist, I've never done so.  With the handful of ladies that did, I am leery of giving second chances.  I'll bet you are, too.

With ladies I know and with whom I have ongoing relationships...it's sometimes a pain in the a$$, but with ladies worth seeing, we just reschedule.  There are many reasons why...and so long as you can reschedule and keep things going, cool at the end of day, usually.  At least for this hobbyist.

Ehh it seems to be a summer trend... Maybe the heat?

This is actually helpful knowledge

That is why I don't book a day in advance because with all that time and anticipation I can't help but rub a couple out just using my imagination about the date! So I pretty much book on short notice unless it is a repeat.