It's time consuming and expensive, unless you have a trading partner. The best information and evaluative software tools are expensive. Training to use tools takes time and can be expensive. Many investors who are new to the markets and who have never experienced a bear market or serious market correction are lulled into a false sense of security by brokerage ads that lead them to believe that self-managed investing is easy. It is not easy if you try to go it alone.
Software is complicated and technical.
No software can be programmed to take into account sentiment, sector rotation, and world events. Technical and fundamental analysis must be tempered with this understanding. If you've got one that works for you, stay the course, but consider augmenting the relationship by better preparing yourself to make knowledgeable decisions and by bringing ideas to the table for your broker to consider. Multiple viewpoints help round out everyone's perspective. If you have millions of dollars under management, a team of brokers will work with your money with discretion privileges and you'll get good service.