How is the next breast to use decided?

The decision as to which breast to suggest next is controlled by the 'Which breast to start feed on' setting.

If you set this to the far left it will always suggests the opposite breast to the one last used.

If you set it to the far right it will suggest the same breast last used.

If you set it to a time value and the feed was more than the amount set it will suggest a swap to the other breast, otherwise it will suggest you use the same breast as last used. It will never suggest you use the same breast more than twice in a row.