For 99% of my posts, even if I’m sharing a blog-like update, I still choose the “image” post option so I can include a custom thumbnail in the header.
All my thumbnails have the same format, I just change the image and the post type (e.g. ‘art share,’ ‘diary’, ‘rewards’, etc.). Here’s an example for an upcoming post:
I polled my patrons and they greatly prefer viewing my art/photos within the post itself by scrolling down through it (using the gallery option instead is very slow and clunky on their devices), so I always use the top photo as a header/teaser about the post. However, unless the viewer is a patron of the right tier and logged in to see it, everyone else only sees a blurry image.
While I use the thumbnails I create to promote my posts on social media, it would be awesome if we could have a checkbox or something to make the first/main photo in our posts public. I think my page would look a lot more intriguing to newcomers if, instead of seeing nothing but blurry images with a lock over them as they scroll down, they actually get to see all these teaser images and understand how many of each type of posts I tend to share. It might also encourage patrons in lower tiers to bump up to a higher tier if they can actually see the thumbnails of posts they might be missing.
I enjoy the format I make for myself, however if Patreon wanted to also add a tool for us to create our own teaser image on-site, that might be neat, too, and save me some time from making my own before writing each post.