My experience is that the long term effects are more than 10x. I heard a joke once : Complicated problems requires complicated solutions. Unfortunately, all pr

My experience is that the long term effects are more than 10x. I heard a joke once : Complicated problems requires complicated solutions. Unfortunately, all problems are a bit complicated if you are a bit thick. The gist is that complexity grows faster than it needs. Ignoring people that can't make things over a certain threshold, there is a large group of programmers that can make things work, but are not able to build things clean enough or put in the effort required to build testable and maintainable code, simplify support and reduce runtime costs. Knowing when to stop and what to spend some extra time on is also important. I'll hesitate to add reducing future development costs, because I've seen too much overly complex code written in a misguided attempt to handle unknown future requirements. All these costs can easily build up to 10x over time. A factor is that a team probably smoothes over the effects of one or two bad coders in a way that it's not noticeable at short term - the code is delivered and the worst bits are plastered over, but the long term performance is reduced.