Stock selection: Better dogmatic or opportunistic?

If we analyze the performance of the broad European or US stock market, we notice that stocks are advancing that exhibit low balance sheet quality, weak profitability, high price volatility, and low earnings growth. However, that is not totally irrational. Most of those are companies that have taken a massive beating on the stock market in the last few years, but are now benefiting from an environment in which greater economic risks appear relatively unlikely given a foreseeable end of the pandemic and still ultra-accommodative monetary and fiscal policy. It makes sense that the companies benefiting from lower economic risks are mainly ones with basically shaky business models – that explains the rapid catch-up of these "ragamuffin stocks" observed in the past several weeks. But the big question is how long a situation can persist in which stocks perform that really should not be in a portfolio in the long term due to their sub-optimal attributes. Should portfolio managers remain dogmatic and rigidly stick to principles that are correct for the long haul?