Short Term Investments

Stocks better as a long term investment or short term investment?
I own stake in a few stocks and I notice they go down for a short period of time then go back up in a rather consistent fashion. Knowing this, is it better to sell shortly before they go down and then pick them back up when they begin to ascend again, or is it better to hang on to them as long term Investments? I know the income taxes vary greatly on short term vs long term investment too, so is it worth it to sell them in that kind of short term manner?
Short-selling is better if you can identify the highs and lows of the market, which is pretty tough and is a pretty large gamble for most people.
Unless you have a system for analyzing info to determine the swings, you’re just guessing and that will likely hurt you.
Merch log 3: Flipping/Short-term investment ~55M profit