I write these guides from the situations that come up in real Shopify work. The answer is usually less about a fashionable tool and more about choosing a boundary the team can live with.
Support is more than fixing a broken button
Useful theme support covers the small decisions that accumulate around a live store: section changes, product and collection presentation, responsive fixes, accessibility, app interactions, and keeping the code understandable.
A good support rhythm
Start with the live theme and the change in context. Trace the templates, sections, settings, and storefront states involved. Make the smallest clear update, then check the journeys it can affect on real viewport sizes.
Leave the next change easier
The best support work does not just close a ticket. It leaves the theme more legible and the next improvement less risky.