I'm not sure if this is a bug or expected behaviour or just a difficult to solve problem so I'm asking here before submitting a bug report.

When using one monitor I can snap one program to the left and on to the right like this:

When using two monitors I still can only snap 2 programs, there is no way to snap to the two middle half screens, which basically makes the snap functionality useless:

Is this intended behaviour?

It does work but you have to be very precise with the mouse on the monitor change edge. Try moving the window very slowly to see. There are keyboard shortcuts for tiling, Super+Arrow Key. I find these easier, personally.

You're right! I tried several times before but I never quite got there. The shortcut is quit useful too. I'll report it as a bug anyways, can't imagine needing to be that precise is intended behaviour.