Why do things more efficiently? It sounds obvious but actually the answer isn’t obvious at all.
The objective isn’t to do more (they’ll just give you more, and anyway you’ll never finish everything). It’s to change the apportionment, so that you spend less time on unimportant and more time on important things, in the same total day.
For example, say I have one hour available and two tasks to do – mowing my lawn which takes 50 minutes, and phoning mum which normally takes ten. If I can be more efficient (or lower quality!) in how I mow my lawn and get it down from 50 to 40 minutes I can then have 20 minutes for phoning my mum. Reducing the lawn time isn’t so we can do more lawn-type tasks, it’s so that I can improve the apportionment of my day. It’s the same tasks (lawn and mum) in the same total time (an hour), just better apportioned.
Your work day is the same. Less time on interruptions and routine admin means more time to think and plan and get ahead and make a difference to the future shape of things.
The objective of time management is to identify what’s important and then to find ways to spend more time on the important things.