Oct. 10 -22; hotel reservations needed or can we wing it?

You should make reservations for Prague, Amsterdam and Berlin at least.

We are obsessively driven these days because of the internet to make advance reservations. So a lot of people do it. We still wing it a lot using the TI when we arrive or by using the phone/internet a couple days earlier. Cannot be as picky at that time but we haven't slept in the train station either. We have had trouble with Amsterdam on short notice but Haarlem is fine. And we actually prefer Haarlem. I think you could do it but you do need to be flexible.

October is off season so wing it everywhere else except Amsterdam; it is always busy there and the only place I ever showed up sans reservation where all the rooms were gone except the luxury ones out of my price range.

The internet has made winging it a bad idea. Yes you will likely still find a room but you run the risk of it being expensive, inconvenient, or both.

DJ

The obvious compromise is to book ahead from the previous stop. Presumably by the time you check out of one place you will have decided where you are heading next? You won't just be wandering aimlessly around then at 6PM think it time you found a hotel wherever you happen to be?

for places in germany (and some other european locations) https://www.hrs.com/ is good. They have a wide range and you pay at the hotel. And in germany many allow free cancelation until 6PM.

the only real problem, other than paying close to rack rate for leftovers, is the amount of time you will spend every day devoted to organising the next day instead of enjoying the day you are in. If you do it all from home that is valuable time back every day on holiday.