I told you before I have to teach a new colleague this year, and I have taught him a period of time, now it's time for checking and accepting his learning work.
One of my friend told me, you can't teach him all of the things, or he will take over your job one day. As for me, I can't accept this point, I think the knowledge you learn belong to your own, no one can grab it off. So I try my best to teach the newcomer all of the work tast, just like I review my homework once again, I give him the chance to deal with any kinds of the job.
Finally, I am sure I make a good decision, the new colleague make his effort to learn the things and really do a good job to return the good news to me. Till now I can ask him to do everything I want, maybe he is still not efficiency, but he can do it by himself, it's a good result for me. In this case, he really help me a lot, both share the work and the pressure for me.
To give the newcomer a chance, you can get back much more than you think.