HPS helpful during veg?

If I'm going to veg with 400 watt MH (HPS ballast w/ MH conversion bulb), is there any reason to switch in the 400 watt HPS bulb like one day a week? Would that help at all, or just be a total waste of time? I was just thinking about it and was curious.

sounds like a waste of time. the MH is more suited for veg than the HPS. switch over to HPS when u start to flower.