I haven't had all the problems training doctors that everyone else has. At 14 I check that skill preference and then get them started and I have had 2 achieve master status by the time they were 20 and the rest are usually there by 34 or so. I think the builders are the hardest because they NEVER stay on task! But it does make it easier to dress them all the same so I can quickly get them back to work! LOL