When do "Buy and Holders" Sell?

I have all my money in vanguard mutual funds and a bit in international bonds funds and savings bonds. I diversified the portfolio into International, Domestic, real estate, bonds, large, mid and small cap funds. I do not need the money for another 5 years. I am a "buy and hold" person, and have done pretty well, not counting the past few weeks. I didn't take any profits when the funds went way up (International/emerging )and I haven't sold when funds way down (Small Cap, Reits). I'm thinking I should have taken some profit, although how would I have know when.... but does a true "buy and hold" loose out by "holding " too long?? I figure the dividends are re-invested back into the funds and I am buying at a really low price.. What are your thoughts people?