10 - 20 minutes
The letter 'A' came off of the keyboard and would not reseat. My granddaughter needed this MacBook for school.
The repair could not have been easier due to the very detailed disassembly photos along with the text describing the size of each screw. Replacing the top case-keyboard took about an hour or less. I would say the only difficulty was removing very small screws located in tight places without stripping the heads. One just needs patience.
The advice I can offer is to go slow with screw removal and keep all screws from 1 section of the case grouped together and place the groups in order of removal to make reassembly easier. Use patience and do not strip the screw heads