I ALWAYS carry on researching - albeit not as intensively - because you DO still get bonuses!
EVERY "production tech" in the game gives you a 2% bonus - Food, Energy, and Construction.
If you research a new level in one of these tech fields, you will gain a 2% production bonus - irrespective of whether you upgrade your buildings or not.
It doesn't sound like much, but those bonuses build up - obviously it is accumulative. I can eventually get my systems running on just one (Working) food and sometimes even energy structure.
The additional population blocks can then go into intel or construction.