Its always a trade-off. Sure, if I see a company I own go way past my 'price target' i'll sell it regardless of the tax issue.
The fact that we are 2 weeks before the new year simply makes me do less short-term trading. Your short-term trading is never perfect, you often sell while the company keeps going higher/etc. The tax impact simply changes the determination point of when I decide to sell since it adds a 'cost' to every sale thus impacting the sell/hold profitability probability matrix.