I talked to one of the owners of one of the well respected broadhead companies and he said that longer heads actually create more drag and resistance on gel tests than the shorter profile heads. The shorter heads have less surface area. The 3:1 ratio is an older standard, before slo-mo cameras and better testing materials than old tires and garbage cans. And, some of the research often quoted is on very large African game. Most hunters in the USA hunt whitetails and good blood trails after a passthru are typically the most desired outcome.
Shorter heads can be made thicker and will never bend or break.
For a while, people thought the Steelforce Phathead was a compound head. They couldn't have been more wrong. They are a stout little head, but finally 3 Rivers picked them up. And if one notices, the Phathead is one of the few with all 5 star reviews. One of, if not the best 4 blade on the market.