When we reach for it
Existing TensorFlow estates, and production serving where the tooling around the model matters as much as the model. In practice that means inheriting a working system rather than starting one, which is a different job and priced as one.
When we would argue against it
New research work. The ecosystem has largely moved, and a smaller community around your problem is a real cost. We will say so plainly rather than quietly bill the extra time it costs.
What it looks like in delivery
Usually maintenance and serving rather than training — keeping a model that works in production reproducible. That includes knowing when a model has drifted far enough from the data it was trained on to be retired — a decision someone has to own, not a threshold that fires on its own.