Background: I work from home. Being on a small team, each of us is on our own projects. Last year I made a giant excel doc to input data for a customer we have and am the only one that has the password for the protected sheets so those collecting the data don't accidently delete the formulas. There are only a handful of columns and rows unlocked for the data entry. Therefore, no one but me knows how all the data is calculated, they just see the end reports. This beast is well over 100 pages when printed off as a pdf. Truly a pain in the ass to create originally and probably took 8 or 9 weeks of dedicated effort.
Task: Well last month the customer decided they wanted some tweaks in the reports that are automatically created from my excel doc. I explained how that small change would mess up the background logic and formulas and could take 3-4 weeks to impliment because I'd essentially need to start over. Everyone including my boss totally agreed and told me to make it my main priority for the month and to skip meetings as needed so I can dedicate the maximum time to making the changes.
The plan: I have a mouse wiggler that keeps my computer active and have my work email connected to my phone. I can look like I'm active all day from our work chat software and can check my email as needed. I took a road trip to see some national parks and visit my family. Joined a few calls while on the road to keep in touch with the projects I work closely with and would reply to a few emails at the end of the day but otherwise I was completely uninvolved for 6 or 7 hours each day. 8 hour days normally, on salary.
The big secret: I only had to change one column's formula. I did it on a Friday afternoon and the changes were already done. It was way easier to do than I expected.
TLDR: told company a project would take me a month to compete. Took me 5 min and I took the rest of the month off.