I was exceptionally lucky. I was sponsored through the CAP509 programme in the early 1980's, arrived with shiny frozen ATPL at base training and after three weeks ground school and a very stiff exam found myself in the RHS of a twin jet sim with a highly experienced P1 converting to type in the LHS.
The highly experienced P1 and the rest of the training team cajoled, caressed and kicked me through the training, then followed circuits at Prestwick, stamp on license before line training.
I had a PPL before starting so was in the RHS of an Airbus with 402 hours TT. I did 20 sectors with a safety pilot on the jump seat, another thirty with a line trainer and then was signed off with the caveat "no auto-lands until trained at first VBC/IBC." 200 hundred hours later I landed the beast alone after the P1 was knocked out by a silly accident down the back.
15 000 hours later I know now what I didn't know then, and I'm still learning fast, and all of my colleagues from the CAP509 course are all senior captains somewhere.
I've looked at the current integrated courses, and while the graduates seem very young they are steeped from day one in the SOP's of the company they are being trained by. They arrive at the base training stage thoroughly knowledgeable about how their company works, then it is a question of learning to fly the aircraft properly, and that skill applies to newcomers and to highly experienced pilots.
Talking recently with the head of training at a large European LoCo I asked about the MPL, and was surprised at the good results his company has achieved with it. And in that case the flying is less than 100 hours with a huge concentration on simulators.
A couple of hundred hours to the RHS of a 200 seat jet may not seem much, but in my view it depends on how that 200 hours is used and how the culture of airmanship is taught as well as how the new pilot is put through his base and line training and up-grades that follow. Where I currently work we require 1 500 hours for a P2 and I'm not sure that is necessarily the best way to go, I'd rather recruit off an assessment of abilities, but then the insurance premiums would go up a long way.