Architecture & practice·Design, structure and tradeoffs
you wanted to change the retry policy and had to read a HTML template to find where it was set.
Separation of concerns
Also calledSoC
Keeping distinct kinds of decision in distinct places, so that changing one kind does not require understanding the others. It is the reason business rules do not belong in a controller and formatting does not belong in a query. The payoff is not tidiness: it is that each concern can be reasoned about, tested and changed by someone who does not have to hold the rest of the system in their head at the same time.