shaded out is much more likely than verticillium or canker.

If you remove the all yellow guys that will increase aeration for the plant and, besides that, will look better and cause less human stress

Watering every 3/4 days may not be enough.

What system used - drip, hand. bucket?

And for how long?

How deep does the soil get moistened?

Where are you located?

located on Long Island, NY (zone 7b)

i have been trying to trim off the yellow turning branches to see if it spreads.

i use a in-ground spinkler system. will need to check the soil depth.

my 4 other tomato plants / 4 peppers amd celery are doing just fine.

Fellow Long Island gardener here. I'm certainly no expert, but I have to say this looks almost identical to an issue I've had the past two seasons with Romas (two years ago) and a San Marzano plant (last year). Around mid July a set of leaves at the bottom or in the middle of the plant would yellow in a very similar manner as your second photo -- eventually it would dry up and die. Pruning affected branches had little impact, as the yellowing would happen again on other leaves and branches. By the end of July I've had to pull the plants.

In each case, other plants in the same bed were unaffected, including other Romas/Marzanos. I moved all tomatoes out of that bed this season.

The bottom picture almost looks like textbook onset of fusarium ("yellow flag", i.e., bright yellow, found on one part of plant/only certain branches/one side of branch or leaf). Both fusarium and verticilium are widespread on LI. Did you buy this plant or grow it from seed? It might be worth contacting your local Cornell Cooperative Extension office.