How do Go's limits work when you mix $15-tier and $60-tier models?"

Trying to work out how Go's limits actually behave when you mix models and I can't find a straight answer. The plan is $60/month, but the pricing table also lists $15 of usage for some models (Luna, Grok, Kimi K3) and $60 for others (GLM-5.2, MiniMax, etc). So if I burn the full $15 on GPT 5.6 Luna, do I still have $45 left for GLM-5.2? Or does Luna usage get counted against the pool at a higher rate, meaning $10 of Luna already ate two thirds of my month? The docs never spell out what happens when you switch between tiers, and the github issue that asked about the limits got closed with no reply. Has anyone actually watched the console while doing this?