Use ～てからは when a change that began at a specific point still defines the present situation — it marks the "after" period as a topic and implicitly contrasts it with how things were before. It suits reporting shifts in workflow, performance or policy in writing and formal speech; plain ～てから is neutral sequencing, while ～てからは highlights the contrast. The main clause normally describes a continuing state, habit or trend, not a one-off event.