On this forum "traditional" practice can mean a lot of different things. Toward the end of the 18th century the toolmakers had trouble welding cast steel to the wrought iron so chisels started being made without the lamination, and there has probably been some production of chisels without lamination ever since. For myself I would hesitate to call something traditional that did not span the 18th century.
I have not seen documentation of the technique Joel mentions (forming the entire bevel after heat treatment). It seems to me that if one were to grind after hardening that it might be easier to grind the back slightly hollow than to grind the bevel. I also think that a craftsman who was making 3000 chisels or more a year might find a way to reduce unfavorable warping during heat treatment.
It makes a big difference if one is going to buy a new set of chisels every year or if he aiming for a lifetime of use. I have some chisels that I brought into service 40 and 50 years ago. Whatever time I spent getting them into service is long forgotten.