I didn't have any trouble completing 18 of these in one night. I was out for.. well, around 10 hours, but in that 10, I had to potty the dogs twice (they went with me). And I swang through a drivethru. And I got lost once. And if none of that had happened, I did do just under four hours of drive time in the route. The first five or so were fiddly, while I was getting used to them and then the rest went pretty quick.
Depending on how close together they are, and/or where they are (traffic related), it would be conceivable to do 40 of these over two nights. I had *a lot* of drive time on my route, and still managed 18.
It also let me claim 18, so I'm guessing maybe they lifted those reqs. I had 48 hours to do them.