Pot size management

[Sue_CT]

I think it depends on you. I have seens pics of experienced people with drip irrigation and feeding setups with quite large plants and good fruit production, although I don't think I have ever seen Brandywine done that way, but it is possible. I think you are looking for a particular answer that no one can give you. Can you duplicate the conditions they get with automatic irrigation and feeding? If so, then theoretically yes. Actually duplicating it will take time and dedication but like I said it is theoretically possible. My suggestion is to answer your own question. Plant a few plants, identical plants of identical size next to each other, one in a 5 gallon bucket or pot and the other in a 25 gallon. 2 two Brandywine 2 Cherokee Purple, etc. Water them the same number of times per day or at least make note of how much more you have to water and feed the 5 gallon compared to the 25 gallon. By Mid July through August, compare the level of work each is requiring to keep them identically moist and fed. Compare plant size and production. Compare disease burden, BER, if any, etc. Then YOU decide if you can do it or not. No one else can tell you if you can or will keep up with an automatic system or not. Remeber you can't just water the 5 gallon bucket more heavily each time and then let it dry out in 95 degree heat and douse it again in the evening. I tried that. It is a recipe for BER. Even moisture is much better than alternating wet and dry.

JMHO

[Growing Coastal]

I have also observed that when a large tomato plant gets dried out enough to wilt it develops powdery mildew, here, soon after.
That is one reason I went to a larger pot size.

[Sue_CT]

Yes, overall disease burden goes up. I have seen bacterial spec in my pots when I had none in my garden also. I have no idea why. But I am still working, not at home and can't possibly keep up with what small pots require to get large healthy plants and good production. Someone else in different circumstances who is more dedicated might be able to.