As stated by a trader on another forum, who cares? Sure the market is overvalued. But if you are trading it, you always want to be on the right side (the market is always right.) So your best gauge of trading success is immediate profits.
When it is going up, get long, when it is going down, get short. This applies to any time frame that you are trading. Wary of the big reversal? Some EW count just told you we completed 5 of 5 in the retracement of the "Grand Supercycle" today? Take that advice with a healthy dose of skepticism until the market proves them right. Anyone position trading and betting that the most recent new high was as high as it could go has been wrong - for a while.
Here's an idea: pull up chart of the s&p500 cash and measure a retracement from the high in 2000 to the low in 2002. We haven't even reached 50% yet. How about waiting for a failure swing on the daily charts to declare that this is just a bear market rally?