2.x branch provides a recipe, with task Storage entity, Flag, and a view.
View on GitLab #3473270People are having issues installing it Status: Needs work.
View on GitLab #3473270I documented how to install with a composer git repo Status: Needs work.
Before working that out, I tested by downloading the repo to /recipes/tasks.
Install with drush recipe ../recipes/tasks.
I have an issue with the sidebar form, after saving, it doesn't refresh the list. If you refresh manually, everything works.
This uses the Add Content By Bundle modules for the Add Task button in views, not Views Add Button, which I'm more familiar with.
There is also a View Tasks Extras on Drupal.orgTasks Extras module, that provides additional config. Best explained by it's readme.
Considerations
For this site, the tasks would be recurring. I could have a form to select the task, then create a Storage entity, which would track the time completed and any notes or score. Alternatively, a flag could trigger creating a Storage entity.
To extend the default config, a timestamp field can be added to the flag, set when it's flagged. There is a configuration option to display the flag form in a modal.