Ok, so I think there are actually two separate conversations happening here.
First, whether 90 minutes makes for a better experience than one hour? Personally, I think the answer is yes, almost always, and especially for new clients. At a minimum, I always recommend 90 minutes for a first meeting. As providers we know what's actually happening in that room more often than not. Most men either get performance anxiety with someone new or they get overexcited and finish faster than they'd like. Then, for a few minutes, you get in your head about it instead of having a good time which was not on the itinerary. Like the OP said, I think you need enough time built in for flirting AND for the refractory period. I've landed on 2 to 3 hours as the sweet spot for a first meeting but that's a recommendation, not a policy. I like options and I just nudge people toward the better one.
The second point, about whether providers should move to a 90 minute minimum as an economic strategy if the economy softens is where I say "absolutely not". That makes no sense. If the economy continues to soften, you protect your entry point, you don't raise it. If your minimum booking is one hour, that's your door and you keep the door open. However, if you don't want 1-hours, then make the longer bookings look better to the point a person thinks, "Why would I bother with an hour?" Shout out to Farrah!
Last point about pricing math... I don't think it's confusion at all. When you see a provider pricing 90 minutes at the hourly rate plus half of the second hour rate, they are probably pushing you toward 2-hours. Look at almost any provider's rate structure and you'll notice the per hour cost drops as the booking gets longer. That's so intentional. The 90 minute rate sitting awkwardly between one hour and two hours is designed to make 2-hours look like the obvious choice. Typically, providers pricing 90 minutes at a flat modest premium over the hour rate are incentivizing 90 minutes specifically. Whereas, the ones doing hourly plus half are incentivizing two hours.
TLDR: you totally keep the one hour in an economic downturn...