When working with large files, I encounter such wasteful actions as expanding/collapsing each selected group of layers.
I find it better to perform these actions in bulk. Here is my solution to this problem. Please vote if you are also troubled by this time-consuming process.
I was going to vote for this but it looks like this feature exists. You just have to hold Cmd/Ctrl while clicking and all highlighted elements will be collapsed or expanded together.
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