Yeah, they are regular, it's just parties don't really campaign for that long, campaign finance laws usually prohibit it by maximizing the amount of money that can be spent. You could theoretically campaign for 4 years, but you can't do it with full intensity as you would run out of money, so parties save up for a big bang before the election, as it probably should be.

That said, there are serious problems with EU electoral processes as well, it's just that they are not fundamentally broken like the US. For example, Hungary's ruling party routinely spends a ton of money on "government communication" that is not technically campaigning on paper just in practice, thus sidestepping campaign finance laws.