A process to allocate tasks based on schedule?
 

I'm looking for a way to efficiently allocate tasks according to my schedule.
OF tasks can get an estimated time. Considering I want to do 5 tasks of 1h, 2h, 30m, 30m and 3h respectively, how could I best use tasks estimated time to allocate them to my available time? It would be time consuming to use another app (like calendar) to check available time against. Could someone do that within OF? Any suggestion?

OmniFocus isn't really great at scheduling. What I usually do is just block out chunks of time in my calendar with an appointment set to show that I'm busy.

I just name the title "Focus Time: Project X" or whatever I want to focus on.

Then I just work inside that time block. If I finish something earlier, I might just choose to do a few more extra things to fill out the entire time.

I've found it better to use OmniFocus as a bucket list to hold all the possible tasks I can work on during my discretionary time. It sometimes becomes difficult to get a really good time estimate. Sometimes, I'll encounter hidden tasks that I didn't take into account. Maybe I expected a report in my inbox from someone else. But the other person is sick today. That means I have to spend an extra half hour to an hour to get all the needed resources before I can start working on my intended tasks. It's all the unaccountable things that sometimes throws a monkey wrench into a schedule that I thought would flow like water.