I’m not sure if this is possible or not but most of the time I’m sending an email Next Working Day at 0900 (probably 90% of the emails I use MailButler’s schedule for are doing the same).
I was just thinking where you have the delayed send button it would be really helpful if you could allow us to add some presets so we can just click and forget. The button would just use settings set e.g. Next Working Day at 0900 or Delay by 30mins.