I cannot answer that from direct experience for the latest models. At this point I’ve got pretty good even to eyeball how to chop the work across multiple sessions myself if needed, and depending on how you work on your projects a good harness configuration with proper instructions to delegate portions to dedicated agents plus periodic handoff to a persistent memory mechanism can get you very far. 1M tokens are a lot already, just try to stay way within it for each portion and avoid the need for compaction when possible.