One thing to remember with streaming. Depending on the provider, you might be limited to how many streams (meaning separate streaming players) can connect to a service at one time. For example, Netflix limits you to two concurrent streams with the basic plan, and I believe it reaches four with the top plan. Other providers have similar limitations, so if you think you might have multiple TVs all watching the same provider (not necessarily the same content) you will need to investigate that provider more closely. But say you have two TVs on Netflix, another on Paramount+, another on Disney+, another on YouTube, there's no problem with that, assuming your Internet speed is fast enough for all those streams at once.
If you are wondering about those speeds, you can use a rough rule of thumb to add your desired streams together. 4K content will max out at no more than 20 Mbps for most providers. 1080 (HD) content should not exceed 10 Mbps. DVD (SD) quality content is around 5 Mbps. So if you consider the worst case of every TV streaming a 4K/UHD movie at the same time, six TVs would require a minimum of 120 Mbps. Considering you want some overhead breathing space, and might still want to be able to browse the Internet, that would suggest at least a 200 Mbps connection.
If your expected streaming doesn't include that level of 4K streaming, you can adjust downward as desired. However, I'm of the school of more is better when it comes to Internet speed. When I switched from DSL to cable Internet, my speed went from 100 to 600 Mbps. Because of upgrades Comcast has made, I now have just under 1 Gbps speed for the same price. Just check around and see what speed is available to you and the cost. I will also add that I found it saved me money to rent my model from Comcast, instead of buying my own and paying for unlimited Internet usage. The modem rental fee is $5 per month less than paying for unlimited use, so I save $60 per year, plus I didn't need to spend $150 for my own modem. And when Comcast upgrades their modem, I get it for free, instead of purchasing another one.
