I am wondering if part of the stutter/shutter issue is using a wi-fi web system like eero or orbi? And, the YouTube TV app cannot handle a wif-fi web set up. I noticed shutter sometimes with Roku 4k stick, but is t=is worse with Amazon Fire 4k stick. Table, for OTA, recommends against wi-fi web, and it must run at 720p to prevent stutter/shutter. Of course, the reason why people have a wi-fi web set up is because a single router may not cover a large house or one with multiple floors.
Of course, a single wi -fi router, with lost of devices, could affect performance of a wi-fi based streaming. device. Even on a wi-fi web set up it can too.
By he way, I have 1GB/!GB service, more than enough for any form of streaming. Also, I have watched locast, CBS All Access and Philo, with no stutter/shutter issues. YouTube TV app seems to need work, more than just fro stutter/shutter. On Roku, the app constantly goes into a blank screen, and you have to force exit it, when you try to change channels.
The service is great, but it has stability issues, as well it seems to work best on wired Internet straight to a router.