Productivity and Competence

I just listened to your podcast on productivity. Set a time, and do the thing in that time. So, I set an amount of time to decorate my classroom for a side teaching job. I’ve never decorated before, and I decided to allocate an hour. Well, that was simply not enough time! The task took longer than I expected, and there was no getting around it; it wasn’t because I was distracted, I just hadn’t realized how long it would take me to cover bulletin boards with paper!
Do you leave room for a learning curve when you’re allocating time for a project you’ve never done before, while you’re developing your confidence? Sure I could have just left half of the work undone, but that would have been a major bummer.