Learn English – “When will you be leaving” vs “When will you leave”

Let’s break it down. “As to” is synonymous with “regarding”, “concerning” or “with respect to”. In a real use case (news headline):

Here's A Quick Explanation As To Why Today's Jobs Number Made No Sense

It doesn’t add much meaning in “as to why” compared to “why”, except for sounding more pedantic.

They're all just stylistic choices, with no difference in nuance of meaning.

The only context where "regular, repeat event" comes into play is when you say something like "The London train leaves at 8 o'clock" - if you don't specify any particular day, the implication is it does so every day (or at least, every week-day - it may leave at a different time, or not at all, on Saturday and/or Sunday).