No problems here. I have a 5 day handling time and usually try to get the parcel sent by the next day. I have recently had a few sales to WA from NSW and they all arrived in 5 days or less. The arrived within my handling time, which the buyers absolutely love.

Posting in a red box means nothing. Just because you say you post on a Sunday, doesn't mean the buyer believes that, given you are sending without tracking. These days, anyone with less than a 3 day handling time is asking for trouble. A one day handling time doesn't earn you any brownie points, it just sets you up for unrealistic buyers, and dinged stars.