So, where were these bottlenecks on what form did they take? Books I have on the type mention no 'industrial bottlenecks' concerning its production, so where did you find this claim?
According to Sharp and Bowyer in their book Mosquito (Crecy, 1995), de Havilland made outlandish promises in July 1940 while the prototype was under construction, of 50 Mosquitoes by December 1941, but the Air Ministry told Hatfield not to escalate tooling too much as the firm might not be able to deliver on its promise. The area that really facilitated production of the type was the fact that major components were sub-contracted and this saved expectations at Hatfield in terms of tooling and staffing for the future. The book also mentions the fact that sub-contracting actually sped production to meet demand and all evidence in the book shows that things happened smoothly as a result of the decision to sub-contract, with companies willing to facilitate this, which meant that the flow of airframes began to meet demand as it was at the time. One area identified as problematic was the Air Ministry's demands for both fighter and bomber types, not being entirely clear of the numbers it wanted of each to begin with.
The following from the book indicates the RAF's receipt of the type :
"After taking their fiftieth aircraft in mid-March 1942, the RAF had fifty more in the next two months, the 101st by 30 May. They had the 408th by 28th November (Hatfield 366, Leavesden 42), and the 1,000th in June 1943 (Hatfield 775, Leavesden 198 by 21 June). Thus the production rate was one a week in late 1941, three a week in early 1942, eight a week by midsummer, 12 to 14 a week by the end of 1942 and double that a year later from all sources."
I'm also well aware that the Lancaster is a larger and more complex aircraft to build than the Mosquito, but the point is that within a similar time period, the Mosquito's production figures are comparable to other types built by Britain during the war.
There are many reasons of course involved, each affecting others.
First of all, manpower specialised in wood construction. While it is relatively simple to instruct a riveteer, it is not so easy to form a cabinet maker.
In the period of the industrialization of Italy (early 50s mid 60s), tens of thousands of agricultural workers went from the deep south of Italy to the north to work at the Piaggio or Fiat factory and it was very straightforward to train and put them in front of a press, or in front of an automatic drilling machine. The same thing can't be said for woodworking: if you put a not perfectly trained and experienced person in front of a table saw, it is most probably he will not only cut the plank, but also one of his hands.
Wood it is not aluminium: it bends, it cracks, it warps, it spilts and an experienced woodworker at first glance "sees" how to cut a plank in order to minimize those defects. Certainly, the use of half-processed material like plywood can help, but up to a point.
When I was younger I was involved in sailing racing and I was a friend of an old marine carpenter.
One day I helped him to replace a rotten board in an old traditionally built boat.
After spending half an hour looking for the right board from a big pile, he showed it to me and said:
"You see, Sir, we will put this board and it will surely sag. But if we put it like this it will tend to tighten the joints and the water will not go in. If instead we put it to the contrary, the board will tend to widen the joints and the boat will leak."
How many years did that carpenter take to figure out which plank to use, and how to set it up on the boat?
Another small example.
To glue a wooden joint perfectly it must be subjected to strong pressure, and to exert a strong pressure either very powerful presses or many clamps are required.
If this pressure is not exerted perfectly in all probability the joint will tend to unglue, with a result not exactly edifying in an airplane.
Anyone who goes to a traditional woodworking shop is amazed by the dozens, if not hundreds, of metal clamps hanging on the walls: so, before building a wooden airplane, you must have the presses and clamps available, and if you don't, you have to produce presses and clamps.
de Havilland had already some problems about this matter
De Havilland DH.91 Albatross Transport
There are many other reasons... I love woodworking, and I'm involved with it both professionaly and as a hobby.