Chápu to správně, že tramvaje projíždí kolem každou půlhodinu, ale do smyčky zpravidla nezajíždí protože jedou dále na Tapešu iela?

Do I understand it well this loop is not normally used?

You are correct, this loop, Zasulauka stacija, is only used when there are obstructions or accidents on the line, like the recent wire damage that happened due to a storm.
Normally this is just a stop along line 2, but it is also one of the Retro Tram destinations, if you choose to order a trip from the transport company.