That I can't say. If you de-tune a gut string down 2 steps when the bass is at rest it will last twice as long, and be more stable.
How long a time 'at rest' to make it worthwhile down tuning 2 steps? I can't imagine you'd want to do this unless you're not playing for a week. I certainly wouldn't think doing it every day makes sense - plus I imagine you'd lose the tuning stability that you've gained by having them under constant tension.
Any other opinions on this?
I've never heard this before.