Sometimes it is ok to move closer and other times it is not. If you are certain the bird doesn't want to recall or that it wants you to come closer, then don't. Sometimes, coming closer and getting that first recall will help encourage a farther recall the next time though. In that case it's ok. Regardless, always try to disconnect the coming closer from the failed recall. For example, after a failed recall, walk away and do something else and then come and try a closer recall.
Motivation is crucial to flight recall training. If the bird is particularly young, don't go too heavy on the food management. If it's a bit older, within reasonable bounds (and ideally with a good alternative test of motivation like doing a trick),
experiment with increasing levels of food management. It is obvious that food based reinforcement will be ineffective after a meal. In the short term, just rely on training for food treats prior to meals. As the parrot gets better at flying and the cost of flight diminishes (stronger muscles, more confidence, etc), you can
look into variable ratio reinforcement and alternative reinforcements. My parrots will recall to me when we are training and they are getting food for it, just for the hell of it, or for attention. Otherwise forget it. However, if I let them get bored enough, they will come just for attention, petting, etc.
It's ok to let your parrot fly to you on its own but it's important to differentiate between that and training. Don't reward those kinds of flights. When you see your parrot look like it's about to fly to you anyway, recall it. Then you can reward and get credit for doing a recall. This also teaches a form of stay as well. The parrot learns to signal you that it wants to come but if you don't recall, then it shouldn't. Don't let it land on your shoulder though. That will lead to a bad habit and will be annoying. Teach it to fly to your hand and then use being put on shoulder as another kind of reward.