If it takes X years experience to gain I-shaped expertise and Y years experience to gain generalist expertise, it should follow that it takes roughly X + Y year

If it takes X years experience to gain I-shaped expertise and Y years experience to gain generalist expertise, it should follow that it takes roughly X + Y years to gain T shaped expertise It might not be exactly linear, but you should consider that by committing to a team of T shaped engineers you’re also committing to a team of very highly qualified and very expensive engineers.