Could do. Just saying that I have never come across one randomly. Not ever.
After the changes to make their detection (for those specifically searching them) even harder, your chances didn't exactly improve in V2.3 - to say the least.
Just do the math :
- 1000km radius Moon
- Surface Area = 12566400 km²
- Ideal case : you can see a corresponding mineral Deposit on the Scanner within 10km Range, thus granting you an instant coverage of ~314 km² around your Ship.
That yields a rough statistical chance of approx. 2.5*10E-05 of finding something after parking the Ship above the Surface at a random location (assuming 1 spot per Planet).
To put that number in perspective :
If you were to put your Ship only over the Surface of moons with a mere 1000km Radius, Statistically you'd only have to do this some ~40000 times before accidentally discovering a spot of Volcanism once, if only one was to exist on that Moon.
Arguably though, typically more than one site of Volcanism exists (a max of upto 3 or 4 have been found AFAIK per Planet), but there's also plain Mineral Deposits (simple rocks) without Volcanism.
Assuming 10 Mineral Deposits of any form per Planet, it "only" requires 4000 landings to accidentally stumble over one on that hypothetical 1000km radius Moon.
If a simple rock isn't your thing to invest days of searching into (*lol*), I'd say 1:10000 is a somewhat realistic estimate for a 1000km Moon hopefully holding 4 sites of Volcanism - but only if all of them held a Mineral Deposit visible on the Scanner... which isn't the case.
So in the end, I'd say roughly 1:20000 is the most realistic estimate I could give for that hypothetical 1000km Moon.
Disclaimer :
Math in public... I assume no responsibility for the correctness of above caluclations
PS.
Volcanism spots I found so far since they were implemented : 27