I think I just realized how Agenda will be useful for me.
I’m a Things 3 user already and I love it. However with very open ended work, such as a thesis, I find that a project gets cluttered with time. Things 3 is perfect for work with less uncertainty and changes in direction where you just need to cross of a bunch of things in succession and you’re done.
But a thesis and much scientific / engineering work is more messy and I think the format for Agenda might be better for that. I’d miss the “Upcoming” view from Things 3, which I use for week planning. I could see myself move away from weekly planning and use Agenda for the “main” work and Things 3 for side projects and more predicable work