In blitz (5 minutes or less), time management is absolutely critical. When I went back and reviewed games I lost, it was frequently due to tactical opportunities or poor moves I made while short on time. You simply don't have the luxury of time to find the best move in a 3 or 5 minute game. If you can quickly find a move that improves your position in some way and doesn't hang material or create opportunities for your opponent, make it, and don't think twice, unless you already have a large time advantage over your opponent. My rating improved dramatically once I focused more on managing my time better.
Largely agree with most of the other advice offered in the article though. It cannot be overstated how much playing with strong players and reviewing your past games (wins and losses) will help you improve and develop a sense for tactical opportunities.