I follow your thinking to an extent, but it honestly seems like you're trying to inconspicuously set up Itch.io game pages to mimic the payment scheme of Patreon ... which subverts the entire reasoning behind Itch.io . I am aware of Patreon and that it exists / how it operates - I very intentionally choose not to use Patreon. I have games on Itch.io along with platforms that rhyme with Beam and Cog and have zero issue with one-time payments.
I'm not saying you can't do this, but it really should have been made apparent. I would've paid for a second chapter or season or whatever, but I'm not going to purchase anything from you again considering you can just decide that whatever I initially paid wasn't good enough for the final product. It's a store, not a subscription and certainly not an auction house.