So if I'm understanding correctly, you guys choose different GF settings for different kinds of dives based mostly on how you have felt after the dives and factors like water temperature and exertion.
Effectively, yes. However, I don't actually "adjust" the GF settings on my computer for those dives with short deco, I just adjust my ascent schedule manually (i.e. my computer says it's cleared but I stay a few more minutes).
I've come up with my ascent strategies based on paying close attention to how I feel after my dives and adjusting. If I felt "unwell" after a dive, I would adjust what I did on a future dive.
To ME, I might choose more aggressive GF settings for NDL dives because I know that the slower tissue compartments don't on-gas as much during a dive that short. So, there is less chance of them bubbling at the end. On a deco dive, those slower compartments are closer to supersaturation at the end and they let it go more slowly. So, I am inclined to be more conservative in my ascent.
Sort of, but you are missing a few things. Anecdotally, based on my own personal experiences, once I've flipped that switch and gone into deco, I need to be a little conservative. However, I have found that once the deco becomes "extreme" (the US Navy has a definition for extreme exposure diving, I'm using their definition here) I can be more aggressive on the ascent schedule.
Please note: I am not listing the GF numbers I actually run, but I am going to throw some numbers down below to make you think about ascent schedules.
So, if I'm doing NDL diving, I may choose to run a GF equivalent of 100/100.
If I'm doing short deco dives (<15 minutes total stop time), I may choose to run a conservative ascent schedule (think something like 40/60).
If I'm doing "extreme" deco dives, I may choose to run a more aggressive ascent schedule (think something like 50/90).
I need to be clear, those are not the GF's I use, I am just trying to describe the ascent patterns I have found success with on the ~700+ deco dives I've done since having my PFO closed in 2014.
I also need more shallow time on low/no helium dives. N2 is a bigger pain to get rid of than He.
My experience jives with that. It's my belief the helium "penalty" is wrong and there probably should be a nitrogen penalty, especially on longer dives.