I'm pretty sure that would get better results than mono fire. Neither of them can win in 4 turns but I think earth deck might have a better chance of winning in 5.
I kept track of turns taken to win to compare my monofire ( with 2 fahrenheits) with monoearth (5 shriekers and 2 long swords, though I'm not sure about the swords). I've only done 25 games with each, but so far fire wins in 6.28 turns on average and earth in 5.74 on average. Fire won only 2 games in 5 turns, and earth was about half and half between 5 and 6, which would point to earth being a bit better.
However, if you consider actual time spent instead of turns, clicking evolve on each graboid will take time that otherwise wouldn't be taken. Not sure how much extra time that would come out to, but I guess it could add up.
Also, going second has the distinct advantage of 1 extra draw, and all but one of the 5 turn wins were games I went second, so the data could be off if I just got more second turn games using earth.
Even with those questions, I still feel earth is a bit better, but maybe it's just because I find it more fun.