No matter what causes distortion it’s gonna happen. Doesn’t matter if you let each weld cool back to room temp before continuing. Physics is physics I don’t like forced cooling because why harden the weld especially a mig weld. The key is not the heat. The key is getting the best fit possible and clean as possible. This reduces heat by keeping the weld as small as possible. The other key is proper hammer and dolly work. This is true for mig, tig, or torch.