Unless you are attempting to no-till seed into existing stubble, all stubble should be worked into the soil, using a fairly intensive primary tillage implement. Packing during seeding and afterwards gives good soil contact with the seed. This is extremely important for good germination and early, vigorous seedling growth. Firm seedbeds also reduce the possibility of planting too deep and firm seedbeds hold the moisture closer to the soil surface. A firm soil is one that leaves only a slight footprint.
Irrigations also help to pack the soil.