I don't find it intrusive and occasionally it's helpful
I tend to agree with you. Although his Magic Ink Universe contains an extensive list of characters and a GOOD cast list would be very helpful in keeping the characters straight as to their involvement in his prior stories.
Unfortunately, his character descriptions are generally limited to the character's physical attributes and often identify who they are related to. This does very little in helping me place them in their roles in other stories.
Personally, I find Uncle Jim's list of characters intrusive, but that is just me. He presents a list of characters from prior stories at the start of a new story. He then presents abbreviated lists of the characters who have roles in the subsequent chapters and he identifies characters introduced during the chapter at that time. If I recall, he also presents the original character list plus the new additions periodically in long stories. The short new character announcements are not a big deal in regard to finding where the chapter's text begins, but I find it irritating to have to page down several screens to find the start of the chapter. Furthermore, when I read a list of 8 or more new characters plus prior characters at the start of a new chapter, I've forgotten their names, height, hair and eye colors, bust size for female characters, etc. before I've even read the first paragraph of the chapter; the details are one jumbled mix of characteristics in my memory. Since I find reading these character lists to be a waste of my time, I make it a habit to just skip over the lists and go straight to the first paragraph of the chapter.