I usually make a schedule on my gcal, but I don't put much effort into being accurate with time estimations -- a couple of quick tasks can share half an hour; larger tasks usually can't be completed in a day so they get whatever chunk of time I feel like allotting them, often 1.5-2 hours. Then I feel like I have accomplished things if I actually get done all my little tasks, and if I actually do my big tasks for at least most of their allotted time.

I've had the same "aha" moment about realistic expectations, and scheduling has helped, but ... it seems like maybe the novelty has worn off or something?