I have done this trick most of the time and did charge or discharge my battery with 0.5 or 1C to get the result faster, However; keep in mind that the result could be a little bit different when you follow up the standard procedure.
If I continuously charge and discharge my half cell at a 1C rate for an extended period, will it cause any problems such as aging or performance issues?
let me start from this point that actually in half cell you can jump from the formation step to the rest of evaluation process, however, it is recommended to do this step even at half cell stage. it will give you the certainty that you get the most out of your material. I mean after testing in a standard procedure, you will get sure that your results could not be better.
Regarding your question about continuous charge and discharge at 1C for extended period, I should say it is really depend on the quality of your material. if your LFP has been synthesized in a good quality, it will not show performance issue, but aging is something that happen while cycling and might happen after long period of cycling. In the other words, I should say if your LFP prepared in a good quality, 1C is not a harsh situation for testing and you can go further in higher C rates like 2C.
I hope got your point and answered your question properly.