It kinda just depends on how bad the conditions are that he’s dealing with. Some soil conditions are so bad that its hard to get anything like that to thrive well enough to produce the biomass you’re looking for….especially if its small plots and you’re competing with deer browsing as well. In those type situations you’re better off adding soil amendments like lime, chicken litter, fertilizer……and let nature decide what is best suited for summer vegetation…..you’re just pampering it along. If I was gonna plant something in these situations then it would likely be millet……but if your field is trying to grow crabgrass in the beginning I wouldn’t fight against it just to replace it with millet. There's likely a reason crabgrass is growing....its because its suited to thrive in poor conditions as a pioneer species. A lot of this is situational though and it just depends on the individual field.