I have a new r58 and bought a selection of vst baskets with it. I have been able to dial in my brew with the 15 gram basket (dosed as marked) to yield 50-60 ml in 25-30 seconds.

My understanding is this should be my goal for that size.

When I go to a larger basket ( I have both the 18 and 20). What should I shoot for? Does time and yield increase in proportion to dose?

Or, am I still shooting for 60 ml in 30 seconds with more "flavor"?

Not sure what to expect or shoot for.

This will teach you everything you need.

Brewing ratios for espresso beverages

Do not use the VST dosing recommendations as rules but guidelines. You do not have to use a 20 gram dose in a 20 gram basket. Every coffee will work better/worse with different doses and extraction yields.

Ok, I read the first few pages of the linked thread. I see it's based on weight of dose to weight of shot.

I don't see much reference to time (perhaps later in the 20 pages)

Does that mean most are pulling and stopping based on color (blonding)?

Your times will stay the same be it a single, double or triple. Run your shots in the 22-30 second range and adjust based on taste.