One of the first skills you need to have in managing your time is the art of analyzing your own time.
When you plan your time, check the time spent on each task after each day to find out what you wasted the most time on and it hasn’t any result for you.
Do this for at least a week. For example, if you can have 1 hour to shop, and you have spent two hours in the store, one hour of your time has been wasted.
Doing so allows you to focus on things that waste our time and have more control over your time.