You aren't doing anything wrong. It is great you have had so much to work on already. Working on several people is a great way to learn. You 'are' learning, as we all are. That involves some time to get a clearer picture of what is going on, and feeling comfortable with it. When you do a healing, you feel for blockages. You remove them. If you scan again, the energy will feel different, the blockages will be gone. That is the most you can do, other than your prayers or blessings you impart on your friend. At that point, keeping those areas open, or any other blockages that come up , open, is a forward involvement. Someone does that for themselves, or with help, or the blockage/injury was such that it is gone.
If the blockage is such that more work is likely called for, a more serious blockage, someone has to stay with it. Either your friend, by showing them some Level I exercises, and/or L2 hands to work on themselves, or you seeing them a few times, or both. Again, if it is a serious blockage, having both happen is great. Some types of blockages or illness, take some time to correct, some are instant. If you cover the bases, open them up, bring them energy, etc., you have done the work. You should be able to feel whether or not your friend is open. If they are open, with no blockages, everything is moving in the right direction. If your friend isn't addressing anything themselves, it is possible for a blockage to come back. Stay connected, if appropriate, and assess their condition, check them out, direct them with some help, work on them again if they are open to it. You will be able to tell if they are "staying" open or not. Sometimes healing is instant, sometimes it can take several sessions. Your ability to detect blockages gives you the tool to monitor progress. Don't assume you didn't help your friend with the flu, just because they threw up. Your helping them happened. I think you are having success, you just aren't seeing it. Again, stay with it. Use the ability to feel the energy, to follow a friends progress. See them more than once if you have a question about their progress. If blockages return, remove them again. Keep this up, have them as involved as possible, stay with it until they are stable and on their own. Keep them/yourself open. The injury to your knee and arm may take some time. Don't just point your sword fingers that those places and think you are done. Check yourself completely on a somewhat regular basis. Keep yourself open. Do the exercises(lifestyle). Be sure to work with your whole system, not just specific problems that you address in a specific area connected to an injury or pain.