I have asked a related question on finding accommodation during road-trip in the Czech Republic. One of the given answers suggests to inquire at the local tourist information centres. Given that I will be traveling during the summer holiday, how reliable is it rely on tourist information centres in the Czech Republic? I know that this approach doesn't work in the south of France, where you really need to book ahead. How is this in the Czech Republic (not considering Prague).
The local tourist information centers won't be able to do anything for you if everything's booked out. I would recommend pre-booking something on Booking.com and then cancelling at last-moment's notice if you manage to find an alternative option.