i had a 2.2 4banger in a daytona front drive one time that had only 4lbs oil pressure at a hot idle.
i figured i would shim up the bypass valve just a touch to improve it. those have the spring retained by a soft plug and a cotter pin.
i fired it up and heard a big POP. shut it down to see what that was, and found the oil filter had burst. and you know THAT mess.
seems i had installed the soft plug backward on the spring. [the spring should have been INSIDE the soft plug with the shim] not the spring, shim, then the backward soft plug.
i wondered why i had such a difficult time inserting the cotter pin to retain the spring.
after i was done re-doing the mess, [correctly this time] i had a whole 10lbs of oil pressure at hot idle ! ran it that way for years after. never blew up another oil filter.........

I had a destroyed 383 that I did the same thing... it didnt even fire up and blew.. the pressure
was over 100 psi when it let go... a major mess... in my drive way.. it took me over a week
to finally get it cleaned up

Just priming it goes about 15 ft, got the oil line in but left the other plug out

Don't feel bad.
Many $$$ lawsuits against doctors, hospitals show that even world-class surgeons leave retractors and sponges inside patients.
The IQ-related problem solving ability (A: designing an engine) isn't closely related to memorizing check lists (B: "did you turn off the stove"?).
Your credentials in "A" are far more important than one failure in "B".

Did the same thing and installed a brake pad backwards. Didn't make it out of the driveway before I realized something was way wrong thank goodness.

Anyone that has worked on cars for any length of time has done something equally as dumb.

Brain farts are why I now use an engine run stand to work out the kinks before installing an engine now.

Nothing more frustrating than spending days detailing parts and engine bays only to have them sprayed down with whatever fluid chooses to find its way out.

Cab this is the reason I like working on my cars, especially painting, or building engines and transmission, late in the evening in my little shop at my house.

I go out about 10pm and work until 1 or 2 in the morning because there are no distractions from phones ringing, customers showing up, wife needing something etc.

If I get distracted and have to leave something sit I don't have the memory that I used to and it leads to at a minimum time wasted rechecking work already done or at worst something like your example.

Despite its popularity, "multi-tasking" does not work.
You cannot give 100% attention to 3 things at once, what you get is 33% attention to each and broken parts.
Don't measure anything while talking on the phone!
When in doubt, make a list and follow it. There is no such thing as too small to matter: when you do these things correctly, your peace of mind is much better.
Military put removable tags in huge red letters like "NO STEP" on the weak part of the plane's wing because otherwise the pilot will put his foot through it, "NO START" on the steering wheel of a race car which doesn't have oil in it yet, etc.

Pilot training teaches us to have priority even though some times we need to be doing 2 to 5 things at the same time, primary is to fly the plane, second thing is to navigate and last is to communicate, talk to the crew, passengers or air traffic control.
I had to learn to write thigs down when I went into management at the phone company so I didn't forget to some things when things got hectic. I also learn to write the date and tine down on them after getting burn by some of my incompetent co workers who like to play mind games
The older I get the harder it is to remember many things
I learn the hard way a long time ago to not do any work on motors with someone in the shop or on the phone

Didn't we have this in a thread a LONG time ago .....Titled " Don't ask Me How I Know

It's all about focus. Even when you are in the shop late at night and alone. Especially when we get older, like you said Cab- . Shoot at my age I forget to write it down. I've learned, finish the job at hand before going on to something else. Then double check everything before moving on. I'm 76 now and have learned you have to treat old age as entertaining. And every mistake as a learning experience. Don't know how much longer it will last, but as of now it's still fun. And I'm blessed with good health. Yes God is great !