actually,the main problem was inexperience.every defence company needs a firm ground on which it could operate.both Tejas and Arjun delay was due to both inexperience,obstruction and everchanging criteria,for which the operators were equally to be blamed.but as they'll gain experience,things will gain pace.look at Arjun 2.
The bold part is what I am talking about. Either something like a joint management committee or direct control by armed forces would reduce all this factors.