Custom variables are where most sGTM containers either become elegant or become a maintenance burden.

The short version: a container the next engineer can navigate without you is mostly a matter of doing the obvious thing carefully. Keep variables small, name them after the thing they return, and write them assuming the next reader has not read the previous ones.

You spend a little more time on naming. You save a lot of time later, and so does the next person on call. That trade-off is the one most teams underweight when they plan the work, and it is the one that quietly determines whether the project ships on time.

If you want a longer treatment, we have a deeper post in the series. For now, the takeaway is small enough to fit on a sticky note: Treat your variables the way you treat your code: with intent.