Is a break every 2-3 hours enough?

[Flutegarden]

Here it is.

Breaks during the day - needed?

Waiting until after FP day to really get into doing my touring plans - but reading on here that most people take breaks in the afternoon because of heat etc… Are they truly needed? should I plan some into my days? It will be me, DH, DS21 and DD8. Will be our first trip - so not really sure what to expect. Originally was thinking just storming through each day - staying all day at the parks but now, not so sure. What have you all done and why?