If you press out the tincture and only have the herbs left, I think all the 'goodness' is in the tincture and there is little to nothing left in the herbs. However, if you do not press all of your tincture, instead just press what you will need in the near future, leaving the rest to continue tincturing... Then you could make a double-potency tincture [described below].

That is my thought on the subject.
Water
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Excerpt from the SYL manual:

Letting your herbs soak in alcohol for fourteen days is an absolute minimum. Richard Schulze usually lets his tinctures stand for two to three months before straining. He has one false unicorn tincture (for women who are threatening miscarriage) that has been sitting since the early 1980's. He dips into it occasionally when he needs some, adds more alcohol if it needs it, and lets it continue to soak.

Some of Richard's students make a double-potency tincture.
They first make a regular tincture. Then, before using it, they add fresh herbs into the tincture as if it were clear alcohol, and then they let that continue to soak. When that is pressed, you have gone through two soakings with two different batches of fresh herbs. What a brew!