This is something that I do with my current planner (paper-based), I always scale the task according to the time needed. I find this more visually intuitive as I can tell at a glance what are the items that take the most effort (and usually the important one) in the list.
It also allows me to search for item to finish quickly (e.g. calling my mum which takes 30 minutes) whenever I feel like in the mode of clearing up tasks.
I am planning to do a "day planner" view where you can see your task in a hours breakdown. I think it will be appropriate to scale height based on the task duration in that view. Thanks for the great suggestion!
It also allows me to search for item to finish quickly (e.g. calling my mum which takes 30 minutes) whenever I feel like in the mode of clearing up tasks.