On my 3rd generation Apple TV, the advertisement appears only at the beginning of the video. On the Roku Ultra, initially and then every 5 minutes
Majority of sales for 3rd gen took place over 6 years ago? The 3rd gen was discontinued and replaced 5 years ago.
I am guessing Alphabet Inc crunched the numbers and decided it wasn't worth trying to change anything.
If Apple tried to force similar behavior for 5th generation devices, I think Alphabet Inc. would take "corrective" action. They have already taken action against Microsoft in the past.
As to videos coming up every 5 minutes, I have only seen that when watching short videos such as 10 minutes in length. YouTube seems dedicated to play an ad at the half way point.
Ultimately, I don't think promoting ad skipping tools will work in the long term. It will just be a cat and mouse game. Rather we need to be asking for more alternatives to YouTube. I think it is the lack of competition that is resulting in the aggressive behavior on the part of YouTube.
What you do is that you are using the chromebook with the Roku website with the adblock but it is the chromebook signal that receives the final objective, in win10 it can be done as well. I only mean Roku the box, it is impossible, not like the Amazon Stick and the new Chromecast with Google TV that you can also do that without having a pc or chromebook. The concept is different.
I recently got a new Roku 4K and noticed the adds on YouTube blew up. I wasn't getting near the adds on my older Roku device. I get the business end of this and appreciate YouTube. I'm sure the strategy here is a monthly membership to eliminate the annoyance. Creative business strategy. Another streaming device wanting there $5-10 a month piece of the pie. - Irrelevant, Inappropriate, Repetitive. All the above !