Problem is, if you always give it to the two-day developer your two-week developer might miss out on chances to improve. One place I worked just billed the cli

Problem is, if you always give it to the two-day developer your two-week developer might miss out on chances to improve. One place I worked just billed the client what we would as the reasonable rate and tracked the rest as training. I guess pair programming is one approach to get around this, you'd probably consume a week of dev time total in your example but it's better than two.