Some issues identified were:
If using schedule send when an email has draft content, post send it’s status changes from published (with drafts) on the grid view and version table to be Published
The "Send info" column on grid view get confused ( possibly cached with schedule sending ). The estimated recipient numbers didn’t match rules in place on the First send.
Something strange with the scheduled start and end date controls or I don't know how to use them - What is the behaviour when a start date is in the past for scheduled sending every 30mins?
Misleading message if you had a previously published email but then create a draft:
This email is currently in draft mode and will not be sent. Once you are happy with the content, publish the email to ready it for sending.