This is a quandary I'm having as well, considering tuning my US/Int'l/Bond mix lazy portfolio. Currently my main one is 65/15/20. (Yes, in part because the SP500 multiple is high.)
But take a step back! Here we are, debating the merits of adjusting, occasionally, by a few percent, allocation across broad markets, on a multi-year "stay" strategy. That's pretty civilized. It is so very from, "Yikes! Something happened yesterday so I dumped it all today, should I buy Walmart y'think?"
Life is good, eh?