The amount of JPEG compression should really depend on the usage purpose for the JPEG, and the contents of the JPEG.
The quality level one should choose when exporting an image to JPEG is highly dependent upon the kind of detail contained within the image.
An image of a smooth blue sky or a sunset sky with large areas of orange gradient should probably use a high quality setting, 90-100. An image that contains nothing but complex detail could probably get away with a quality setting of 50-60, possibly even lower.There is no single "best" JPEG compression setting, and depending on the type and complexity of detail(or lack of complexity and detail), you may find yourself using 40-60, 70-80, or 90-100 as appropriate for the photo(s) you are exporting.
Here is a test with quality from left to right: 10, 20, 30, 40, 55, 70, 80, 90, 100%.
File sizes for the full files are: 210k, 278k, 347k, 477k, 601k, 709k, 987k, 1.7M, 7M.