You should read Investing Fables by Damodaran. Assuming of course that you have not ever read it. If you have, you must re-read it.

Let us look at some of the myths of investing….

Actually all of them are true, however, the catch is that sometimes it may not be true.

1. Shares always outperform bonds over time: true. Assume that this is true only over 10 year periods, and you held it for 9 years and 1 month YOU COULD BE COMPLETELY WRONG. Exactly why you should see discrete returns as well as cagr.
2. A bad year WILL be followed by a GOOD year. Though normally true, sometimes a bad year can be followed by a worse year and then by an ordinary year and then by a bumper year. Using past data to guess about the future is of no use.
3. A good share is a good share. So you can buy it at any price and hold on permanently indefinitely, and maybe for life.
4. PSU shares are terrible and is always a sell. It should never be bought. – The truth is at sometime value emerges in all shares. So even though a PSU bank like Icici may not be a good buy even at this price, SAIL maybe a good buy! Do not generalize.
5. Large cap will always under perform a Midcap and a Mid cap will under-perform a small cap. Sheer bull shit.
6. When there is performance rotation, you should rotate your portfolio! Let the market do it – you can sit tight.
7. You can’t time the market
8. You can time the market
9. You should do a SIP for each goal
10. Fund managers give you better returns than what you can get investing directly.
11. You cannot / should not do direct equities by yourself. Only fund managers can.

be careful….