Road trip - how long of chunks?

Me

We are planning our summer vacation and debating flying or driving to our destination. We prefer to drive / camp versus fly / hotel, but this will be our first big trip with our two kids. They’ll be 2 and 4. They’ve done about 4 hours in the car without breaks with no issues. This trip would be 26 hours of driving that we would obviously break up into smaller chunks and overnight stays.

How long of chunks have you driven with your kids?