"However, if you set a goal to spend 3.5 hours in your code editor every day"
I would be careful trying to set up such metrics for yourself.
I can stare for hours at code and not getting anything done. Then away from the screen on a walk or sitting down with pen and paper I solve the problem and implement it in 15 min in code.
My point is, I would focus on a tasklist. Clear things to do at once. (Or in parallel if they are trivial.)
Getting things done, not spending time doing things.
Some days you will quickly burn through six tasks on your list because they turn out to domino or all be easy or something else. Sometimes, a single item will take three days even with honest effort and deep work.
If "tasks done" is your metrics, you will get just as burned here.
As with all long-term habit building, I think the key here is identity forming. Be convinced that you are a person that (for example) cares about exploring their field with side projects and then ask yourself: "What would this person do?"
If you believe yourself, you will then both fight through your tasklist or do X hours of honest works and find that the actual system does not even matter that much.
I would be careful trying to set up such metrics for yourself.
I can stare for hours at code and not getting anything done. Then away from the screen on a walk or sitting down with pen and paper I solve the problem and implement it in 15 min in code.
My point is, I would focus on a tasklist. Clear things to do at once. (Or in parallel if they are trivial.) Getting things done, not spending time doing things.
Otherwise I agree to your post.