This is one Golden Rule i've learnt and in process of mastering and applying. Never Ever let your money sit idle.

Typical mistake which i myself do is Sell Stock and let the cash sit idle to catch the next fish. And in process what happens is Stock Sold moves up and I end up missing the movement.

This is not to say that go against the "Stop Loss" Rule of investing. But it is applicable only when you either:

• Decide to Skim the milk aka sell the Profit Stock Or
  
• Sell Stock which has tanked substantially (Either due to Stock Market Crash or not using Stop Loss)

Definetly there is risk of stock you are holding moving downward, but here in either case you are in good shape.

• For profit making stock, you are going to lose part of profit but not the investment.
  
• For tanked stock, it wont make difference as the upmove potential will have more weightage than downside