Less energy to change solvent into vapor than water- into vapor. Amount of heat energy required to raise one gram of liquid one degree C specific heat SH SH of solvents . 3x more energy to raise the T of water than T of solvent. Water escapes more easily from ink film than solvent. Water based inks can be run at rate equal to or faster than solvent based ones.
Answer depends on type of material.
Tonal quality of ink film depends on pigmentation, percentage of solids in diluted ink. The tonal quality of solidified ink- density and thickness. To create equally dark tones at all types of substrates- to apply a thicker wet layer on more absorbent substrates. Solvent Ink Mileage - Ink Application Chart for obtaining a uniform tone for rotogravure. Different gravure cell will create different ink mileage.