I am not a very good serial reader, so technically sporadic release schedules don't impact me very much, as long as every X months I can go back and read a bunch of new stuff. But webcomics in particular are canceled and abandoned so quickly that you can really lose readers like me, the occasional bingers, if you go too long without an update. Normally, if I see a comic that hasn't been updated in 4 or 5 months, and nothing in the creator's social media or blog says anything special, I tend to say, "Oh well, this thing's probably dead," and leave it at that. That's especially true for stuff I haven't started yet, and I assume it's true for most readers.
For web novels, prose is honestly so much easier than comics that big breaks are tolerated a whole lot less. You're expected to have a backlog and to keep consistent updates, fair or not.
I don't think having a specific schedule is all that important unless it helps your own workflow, but being consistent (such as 2-3 episodes a month, as you say) is still pretty important if you want readers to keep following and then to draw more readers over time. You don't HAVE to do this, but the story will have an easier time if you do that. I also think buffers are important no matter if you have a schedule or not, because you always want to have backup updates just in case something happens.