What percentage of people do you think actually use 16 character passwords?

Probably pretty low.

I use 64 character passwords, or if there is a length limit, always the longest possible. That’s the beauty of using a password manager :)

Do you use 64 character master password?

One advantage about having memorized a bunch of poetry back in the day is I have a lot of secure long passphrases to hand

Aesop, my author, makes mention of two mice and they were sisters dear 1234567890123456789012345678901234567890123456789012345678901234567890

70 and little effort

I consider mine pretty long, and it's right around 30 characters.

56 billion md5 hashes per second for $1.80 per hour at OVH. (single Nvidia Tesla v100 GPU)

Still a no-go for plain old brute forcing all a-z combinations. But, if your password is some combination of actual words, common keyboard sequences, or anything else in a password dictionary, it's cracked pretty quick/cheap.

The best I could find is this

https://stackoverflow.com/questions/10041298/how-to-recover-...

But can you show me the way how you'd go on about this? Really curious.

You can't. That's the point of the post. There is no known feasible pre-image attack on MD5.