Add this script to TamperMonkey (Chrome/Firefox plugin) to automatically select working hours.
Import plugin.js from the TamperMonkey dashboard. Go to the working-time-selection page (choosing the right month) and activate the script; it will start the automatic selection (saturdays and sundays are not considered).
The default configuration is the following:
var HOURS_PER_DAY = 8;
var ROLLBACK = false;
If you want to rollback (all to 0) set
var ROLLBACK = true;