If a prayer requesting daily help with something is launched, will still repeating it on a daily basis add anything to the effectiveness?

This is very much the case, because each and every renewed request adds additional intention with your personal energy behind it. This will be added to all prior prayers that were launched with the intention of the moment. The consequence of this, is that they can be summed together so each prayer becomes not one, but two, then three, then four, then five, and so on, adding an additional increment of personal intention with each repetition of the prayer. They will gain in power accordingly, and reach, and anything not needed will help others. So this is a fine idea indeed. In addition, it serves to keep the partnership going and in mind for all those things that might come up on a unique or unexpected basis. When there is a threat or stress of some kind, it will be much more likely that a person will think about involving Creator to help manage things if they are engaged in a daily ritual of making prayer requests for many things. It will then be second nature to turn to the divine partner in a time of need, and the sooner the better is a good rule of thumb, because it is easier to prevent things than to undo them.