WieWaldi
I only enter pieces into MuseScore if it's my arrangement of pieces for other instruments . Not the whole piece all at once but sections. Usually just the measures I'm working on. Using a MIDI keyboard is easier for entering than using a computer pointer or keyboard keys. I don't usually practice a new piece more than half a page a day so up to 20 measures at most.
The last piece I worked on has a lot of note runs crossing over from the 1 staff to the other. Need to redo the notes to be more readable. Found it hard to read off the original and I don't want to see pencil markings all over the page.
When a piece is on paper, you're stuck playing it as written. When it's in MuseScore, I can easily transpose it to another key or make note changes and reprint the page. Like a version of "Happy Birthday" in the key of F to C.
I occasionally find mistakes when downloading sheet music on PDFs. Instead of getting a paper copy and crossing out the mistakes, I'd import specific pages to a computer paint program and fix it before printing.