Traders try to time the markets by using technical analysis to tell them when to buy or sell the market. As such the average holding period for traders can be anywhere from intra-day to weeks or even months at a time.  Investors are much less active and only trade when they have to re-balance their portfolios, employing a "set-it-and-forget-it" mentality.

This is a difficult question to answer because it depends on whether a trader is highly experienced and has a competitive timing model.  If so, the market timing model should exhibit much less volatility than a long-term investment approach. Also in question is whether the investment asset allocation is properly balanced and well diversified.

Yes it is.  It is not a market timing model.  To run the WMB portfolio, you allocate to low-cost ETFs across the major asset classes (stocks, bonds and gold), and leave it alone until year-s end.  Then, all you need to do is re-balance the asset allocation weightings by selling off some of the funds that experienced gains, while adding to the under-performing asset classes from the previous year.  As a passive investment strategy it is much easier to run than a market timing model.  

Market timing requires that you have a highly competitive model and that you can run it faithfully through good and bad times.  Every timing model experiences "funk" periods, and few traders have the discipline and faith to stick to out-of-phase models once they experience significant drawdown periods - as all timing models eventually do.  

Trends in all the major markets can clearly be seen on long-term charts.  They are much less apparent on charts with shorter time frames - such as 2-minute, 5-minute and 15-minute charts.  The trade-off for validity or reliability of the directional signal is that the longer-term charts have much wider price swings in percentage terms.  A high-low bar on a monthly chart may be as wide as 10% while a 5-minute chart may be only 0.5%, for example.  So you have greater risk control on short-term charts but the noise factor (i.e. the randomness or chaos) is much higher.      

Studies show in fact that women tend to be more successful than men when it comes to investing, probably because hormonal differences cause younger men to speculate, and their success rate is much lower for most traders than it is for investors.

The answer is to this question up to you. But keep in mind that the failure rate for traders is much higher than it is for long-term passive investors.