If someone consistently does really long threads, you might want to let them know you enjoy the threads but are having trouble with timelines being swallowed up by them.
There are other servers with higher character limits, other platforms like @writefreely which are specifically for long form posts, and if they have a wordpress-powered blog they could use a plugin so that it can be followed from Mastodon etc (more info: https://fedi.tips/wordpress-turning-your-blog-into-a-fediverse-server/).
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