Good

How can I find the directory where the files are saved by default?

It's little boring to disable an addon icon from tab context menu every time manually.

Good idea in general but it seems to have problems with pictures, just an example

https://www.rotan2.pt/

Only the big picture at the top is visible after saving the page (and the text columns are changing from right to left and back again after the positions where the pictures are at the original page), no other pctures are shown, I checked ticking and unticking the picture options "Saving delayed pctures..." (not sure about "delayed", here in German "zurückgestellte Bilder") but this does not make any difference

UnMHT on Firefox 56 saves the page with all the pictures and I see it exactly as on my screen before saving it including the text columns at the right positions, too. (page saved with SingleFile is about 67 mb without pictures, page saved with UnMHT is about 44 mb and has all the pictures)

Edit: It was not meant as a bug report.

Website see above saved with SavePage WE (never used so far) is much smaller than the one saved with SingleFile but otherwise exactly looks the same that is without the pictures etc. No idea why, not comfortable of course, seems that the mht format was the much better option for me at least

This "data URI scheme" puts too much crap into the webpage which makes it unsearchable by Windows Index.

Take to much time for saving pages