Hi Eric, I only know 3. Don't think any are a "default" but out of the 3 I know and use, 2 are almost about the same as far as how often they are used, and the 3rd very rarely.
If I'm going up from the A, I just add the side right hand key as this is the fastest and smoothest from that position.
If coming down from the middle C, I usually hit it with the left index finger, covering the 2 notes at the same time.
Of course these can interchange depending on what you're doing and where you're going. I would say these are the 2 I use 99% of the time.
Hope this makes sense!
Johnny
