So I've decided to do a deep dive with alchemical sourcelinks.
TL:DR: needs a big buff for blended potions to be worth it
Math:
75 per potion dose/bottle
for each effect,
+150 for the effect itself
+duration (in ticks)/50
+250 (if level 2)
add all that up and then multiply by 1+(NumEffects*0.5). So 2 effects is a 1.5x bonus. 3 would be a 2x bonus
so.. real numbers:
mana regen gives 297 source
spell damage gives 297 source.
take 3 of each and meld together and you only get 778 source. compared instead to 6 individual potions which would be 1782
the book implies that the intent is to be worthwhile to use bigger and more complex potions, but the math doesnt work out