What’s the consensus for post setting?

We used to dig a 3 - 4ft deep hole, stick the post in, and fill it to the top with bags of dry concrete and keep on working.

Now it’s my understanding to put 6” of gravel on the bottom and do as described above.

But

Someone else is telling me to put a bag of concrete in the bottom, put the post in, and fill it to the surface with gravel.

Others are saying, don’t put a wood post in the ground, pour a concrete footer and set your post on it at grade.

This will be 6 - 6x6’s for a 10x20 shed foundation.

So, what is the preferred method for setting posts these days?