Oh yes they are. Occassionally when I am on a device which doesn't have an ad-blocker. I witness it and I am always left feeling shocked at how many ads Youtube can have. We really don't know the plight of so so many Youtube users. I feel sympathy for them and want to hug them and install an ad-blocker for them.
I actually used to install Revanced for all the relatives who ever complained about Youtube and some who didn't even ask! I just feel like Ad blocker is such a useful thing that I can do to people that I care about who don't know deeply about it.
I must say that it is one of the top entries of lists of most useful/time-saving things I have done in actually saving anybody's actual time.
I express gratitude towards the universe for Ublock Origin. Words can't comprehend how much I love it.
Last time i tried to skim through a longer video on non ad blocked youtube i got two ads every time i skipped. Ended up watching more ad than video... at least until half way through it when I gave up.
And even if you watch one without skipping I'm not sure the amount of ads is even legal in my jurisdiction.
Pay for Youtube premium you say? But I only use it like once per month anyway. Easier to just not try.