Air is a lousy thermal transfer media, an oven is not ideal for this task.
Volume absolutely makes a difference, which is why “stops producing CO2” (bubbling) is the gold standard “am I done yet?”.
You were worried about the consistency/texture?!?
Rather than “fuck, it’s not actually decarbed, these gummies aren’t gonna get folks high”?
I assume by “test dummy” you were planning on a bioassy. Try bromcresol.
Have you read any of the following threads?