In the in-game manual, it is stated that while using Overdrive with a Skell, the duration may be sometimes increased:
Extending Skell Overdrive
A Skell's Overdrive mode will be extended randomly.
Unfortunately, that is all that's mentioned. Similarly, the wiki provides no further information.
So, what is the chance that Overdrive is extended? Is it even a known value?
Additionally, are there any factors that affect this chance? (Skell type, gear, etc.)