Actually, that's not a problem just there. Everywhere has a slow season just like many civie jobs can. For escorts everywhere, Oct - Jan is the slow season. Men start to remember that big holidays are coming up and traveling, plus more accidents that would require sudden financial needs happen this season, so people pinch their pennies. Every city is known for lack of pre-booking.  
Some men like to pre-book, some men don't, it's not regional. I would say the problem is more that cities clients don't take care of their locals so then those locals become touring girls b/c they can't get enough business. If guys always go crazy over the new thing in town, you'll lose all your regulars in the area, then when the touring girls think you're dried out, there's no one left for all that last-minute scheduling every loves so much.  
For the record, spring and summer are the most profitable for ladies b/c many guys break up with girlfriends or divorce over holiday stress and or/not wanting to buy presents..so then when Valentines day and all that comes around and they have extra income..guess who they call? February - May/June are usually the best time for ladies to make money.  
Just my 2 cents after keeping about 4 years worth of nerdy statistics on it. lol.