Quote from ang_99:
Is there anything to them or is it just more hocus pocus?
many will say they have value of course, studies of round numbers show they have no more value than any other number. I have posted such a published longterm study at least 1-2 times in the past here
Do a serious backtest of at least 100-150 examples of different instruments (at different times/dates!) comparing to other numbers using the 50% retracement. You will find they are nothing special.
If you are going to buy retracements, don't focus on a number. It is likely more useful to examine that instrument's recent movements as well as S/R...