Curious, what kinds of tasks do you do that require such a large context window? Anything specific?

for me it's often codebase decomposition.

it's hard to modularize a monolith without keeping large chunks in context at first pre-delegation; the orchestrator -- however you implement it -- needs to carry as much of the original thing as possible into context and big monoliths make this task heavier.

so, tl;dr : I use a lot of tokens re-writing legacy codebases that were constructed with very little CS training in some huge spaghetti fashion by random people around the world.