This is more about ligatures as a typesetting artefact of kerning very tight character spacing
https://xkcd.com/1015/

If you hate someone, teach them to recognise bad Kerning.
I earlier was writing about ligatures that are part of spelling or calligraphy style. If you notice typesetting ligatures, rather than author generated ligatures, that are the result of kerning with small letter spacing then either they are badly done or the character spacing is too tight.
Any font face at a particular size and resolution has a minimum spacing for readability. There is a maximum spacing for readability. Note these spacings are related to the visible size of the lettering. Lower resolution printing limits the minimum spacing.
I read one and a half ebooks since I wrote my original piece. I didn't see any of these typesetting kerning induced ligatures. I guess the Georgia embedded in the epubs converted by Calibre aren't doing the very tight spacing that needs 'f*' ligatures.