According to this paper from 2025 "The metabolic costs of goal-directed cognition are only 5% greater than the ongoing costs of resting neural activity and homeostasis.".

Zoning out doesn't change the energy consumption of the brain that much.

https://www.cell.com/trends/cognitive-sciences/abstract/S136...

https://pubmed.ncbi.nlm.nih.gov/39809687/