Merge folders on Mac
Because I use this like three times a year and always have to look it up: When you want to merge folders of the same name on a Mac (e.g., two identically named folders where you want the contents of Folder 1 and Folder 2 to be in Folder 2), hold down the option key and drag Folder 1 into the container directory of Folder 2. You should see the option to merge.
Note that this is a copy merge, not a move merge, so you'll need to delete the source files when you're done. It also appears to handle recursion properly (so if you have nested folders named the same, it'll give you the same option).
Did I almost look up a whole app to do this? Yes, I did. Is it stupid this isn't one of the default options when you click and drag? Yes, it is.
This post brought to you by Google Drive's decision to chunk download archives separately (e.g., it gives me six self-contained zips rather than 6 zip parts). Which is great for failure cases but awful on success.