Since"West coast" people were mentioned in the OP,ill stick with them,since they are more my area and most studied group.The bow lengths of these people were disigned for their hunting method and style.If someone ever had a chance to examine ancient hunting sites and have elders that used them,educate you on how they hunted them,it makes perfect sense.I have examined stave trees,where a longer stave could have been extracted,but were not.That,combined with availiable wood species and climate,dictated,that a sinew backed short bow was the ticket.There were longer self bows used by people,in more humid climates,further north and south,as was mentioned allready,but in the Great basin and surounding areas,the short sinewed bow was the norm.
Especially,in the great basin area,hunting was done communally.Most often at certain times of year and by drives,that brought the larger animals into traps or cliffs,that had smaller rock blinds at the entrance and possible exits.The archers,were concealed in small non conspicious blinds that would not have accomadated a very long bow.To shoot from these small blinds,the archer just barely cleared the top of it,for the shot,to avoid flagging the game,any more than necessary.Most often,the large game,of this region,was pronghorn,and we know how jumpy they are.A heart attack waitin to happen.Contrary to popular belief,Mule Deer,were not as common in this region as they are today.Most of the old skins,were of Pronghorn and Mountain Sheep.