Time is the most precious commodity. How you spend your time determines your success. Is time spent on vacation time well spent? Yes it is, only when you are able to relax and recharge. If you come back tired, then it is time wasted.
I think I will not lecture you about how a Muslim should view time. Time for a Muslim on earth is to gather as much good deeds as possible while worshiping and believing in Allah etc.
In this age of computers, organising time is easier. I use to use google calendar a lot but I have stopped using it. But whatever methods or apps you use, these are factors to consider.
Ease of use
It must be easy to use. To input the parameters like date and time for eg.
It must let you see your schedule in different magnification. Day, week, month and quarter and year. Maybe.
There are things you do everyday or once a week and sometimes, you forget them because the system does not add them automatically.
A strike pilot know when they will reach a destination by waypoints. GPS when riding uber also can tell when you are reaching. This concept is useful if you want to be on time everytime. It could be by way of instrumentations or just by calculating mentally how much time you have left.
This is my solatime project. In the first version, I find the traditional analog clockface better than a digital watch because of the visual effect. It looks like the pilot's radar. The radar can be adjusted to how many km visibility. It can mute some things so that you can focus on a particular objective.
However, I think the ETA factor is more important. And the focus is there in this version.