No. If you're not suiciding siege weapons, you're actually not using them effectively. It has nothing to do with planning. Without artillery, you would have to have numerical superiority and technological superiority to the units defending the city. When you can suicide several siege weapons at a major city and then simply use your units as sweep-up crews, that's when you plan the battle right. The only alternative is getting stalled when on the offensive because your main force was heavily wounded going Stalingrad on a heavily defended border city.