My question is not about samples
Unfortunatly it is all tied togeather. Sample rate, samples, buffer size, number of screens are all related.
I cannot use the correct timebase to capture a signal and have the scope continuously record.
You can. But you can't expect a scope to be sampling at a rate of 1us at 1milliseconds a division and let it run overnight. Edit: And expect it save all those screens.
If I am scoping an ignition coil or injector at 1 millisecond per division,
For an intermitant fault that is an incorrect set up and the chance of hitting the space bar before the capture is lost is unlikely. You can still get 1 Mssec (for ignition) but use 10 sec a division. Thats 3 screens or 30 seconds of capture time, using all four channels. I have only used this as an example as this is my current set up for the problem I'm chasing.
If I'm correct the pico has two ADC's for the four channels. So it also depends on how many channels you are using.
Each set up has to be tailored to the specific fault you are looking for.
There is only a certain number of samples any scope will hold in its buffer. And the Pico is a giant for buffer size and is what most scopes are missing.
As mentioned, always check the properties tab and a good tip is to use a trigger