Stressed plants do set more seed (fruit) .... think survival by passing on their genes onto the next generation. That said, you will get a more consistent crop throughout the growing season, even in temps above 90° by giving them adequate water.
Also grow indeterminate tomato varieties for season long harvest. Indeterminates will continue to produce until frost where as determinates pretty much give you one big crop and are done.
Exactly, the stressed plant is thinking survival.
But plants won't produce fruit when temps get above 90*. The heat causes blossom drop. Its a thing, google it.
I grow indeterminate plants, have for the past 20 years. The facts are, if the heat doesn't get them the blight will. My plants are done by the end of July.
And there's no cure for the blight. I know, there's heat treatment, blah blah blah, I've been through everything including mulching the entire garden since the blight is soil borne.
To beat the blight, just over whelm it with numbers of plants, harvest what you can.
On top of all that, if a plant does survive the summer here, the tomatoes it produces in the fall are small and take a long time to mature. Its really not worth the effort.
If this is a bit testy, well, I don't need to be schooled on tomatoes. I've been at this a long time. I'm no nooby. But , thanks anyway.