I have a mate who let me in on the secret formula. When looking at a project, double the number and go to the next highest unit.
For example - if a job looks like about 10 mins work, it actually takes 20 hours to complete to ones satisfaction. If it looks like a 2-day job, it will take 4 weeks. You get the idea.
The problem is the actual job doesn't take up an enormous amount of time. What takes up the time is;
1. Finding you're stymied by conflicting information/wrong parts/assembly matching problems/etc., that means work on the job has to stop, and the problem sorted, before continuing.
2. Going to use a tool that promptly breaks down and needs to be repaired/replaced before you can continue.
3. Going off on a search for the correct part that takes up an interminable time and much to-ing and fro-ing before the correct part is finally sourced.
4. Waiting for crucial parts/components to be delivered. Usually sent the long way, via camel pack train through the desert, before it finally arrives.
Also delayed by multitudes of delivery system depts along the way that all need to inspect said part to ensure it is not a bomb/gun part/drugs.
Not to mention the time spent by the part occupying bins in said delivery systems, before anyone gets to handle it and process it for ongoing travel.
5. Filling out the "necessary" paperwork and records associated with the entire project. Omitting one step in this process leads to more delays and frustration.
6. Having "mates" turn up, who have little to do, except BS and "shoot the breeze" and generally waste your valuable time, when you have set a completion stage for the project for that particular day.
Generally, and unfortunately, those "mates" often can't be trusted with helping with the project, for fear of setting it back by days, due to their incompetence with tools.
Not that they are usually inclined to assist with jobs anyway, their job is just to talk.
7. Having to leave the project to attend to pressing family matters - things such as MIL's birthday party, usually held 400kms away and necessitating 3 totally lost days on the project.
Keep at it, Sunfish - "projects" require stamina, perseverance and total dedication (and probably "fixation"), beyond many mortals ability. The end result is usually worth it, if you can see it through to completion.
Enduring the sickness and loss of a loved one is certainly a major burden one doesn't need, when trying to complete a major project.
It also helps to remember that only one bloke is putting the project together - when factories usually dedicate a team of people to the project - which still takes months to complete, anyway, despite the numbers on the team.