I think any holidays big holidays makes the market bleed, Valentine's day, Christmas and New year.
Most of the time when this holidays come the market bleed or drops down might just be a coincidence or maybe investors are just taking out a portion of their investment to celebrate.
You have a valid point. I think it's better to sell before these holidays and buy back during the holiday if even if one isn't going to celebrate.
Although, I'm not sure if it's always gonna work out. But if worth risking.