I'm wondering whether the ability penalties from a Sands of Time spell can be stacked with successive castings. All penalties, especially unnamed ones, normally stack don't they?
This spell accelerates a creature’s aging, rendering them temporarily withered and haggard, applying a 1d6 penalty to Strength, Dexterity, and Constitution. This penalty can’t reduce any of these scores below 1. This penalty lasts for 10 minutes per level.
Ughbash is right. Penalties or bonuses from the same source don't stack.
Also note the ¨This penalty can’t reduce any of these scores below 1¨ part.
So even if you find another spell/effect to ´stack´ penalties with (or damage, which inherently ´stacks´),
The penalty of this spell will not contribute towards reducing any ability below 1.