RE: Why 3-4 bows are "must shoot" before buying?
There are no bows that meet the needs of everyone. The 3 or 4 "must shoot" bows may not be what you prefer. If you simply want to base it on popularity, then shoot Hoyt, Mathews, Bowtech and Martin or PSE.
More important is to pick the best bow shop, with the very best service and buy whatever you prefer from their lineup. Great service, set-up and tuning help with do far more for your shooting then any particular brand will.
Good luck,