It will depend a lot of the Bitcoin price. If I bought for $500, when it hits $800 and I know the price won't be stable, I sell all, wait the price down again and buy more one time. If I know the price will be stable, I just hold for the next "flash" pump. This way it's possible to make a good profit, the currency volatility allows we to do it, it's amazing.
But I think it also depend on the amount of your investment.
If you have a good investment then you can buy bitcoin in any price and if the price does down still you will have no worry to sell it because you can afford to to buy more at lower price.