Man, that's the story of my life with pretty much any project I touch. There's always this huge gap between what I think something should take and what it actually takes. It's like a universal law of home repairs and tech projects that everything takes three times longer than you expect. The funny thing is I keep forgetting this pattern every single time I start something new. I'll be all confident thinking "this will be quick" and then four hours later I'm surrounded by tools and questioning my life choices.
Honestly, "questioning my life choices" is exactly where I end up too. I started doubling my initial time estimate before I even pick up a tool, and it saved my sanity. Now if I think something will take an hour, I plan for two and actually come out feeling good when it only takes one.