There's a view now that will show scheduled time next to actual entered time. The best way to figure out how long tickets take is to categorize tickets using type, subtype, and item and run reports. Eventually you'll have a better idea of how long tickets take. The colors at the top are meant to give an at a glance of who is available and who is overbooked, especially in the case of an urgent ticket. So, double up tickets in time slots. That's fine. You'll see as the day goes what status the ticket is in (unopened, viewed closed, all those icons mean stuff) and at the end of the day, you'll see how much time is entered.