When do I cash in for my mid-term trade?

I would like to cash in after other mid-term traders have cashed in as I know mid-term traders are less likely to cash out easily. Frankly, it is not easy to tell when the mid-term traders have cashed in.

One way is to look for a single-day volume spike. But, sometimes, mid-terms traders do not rush in in a single day, resulting in no volume spike. In that case, I will have to look for crossing of some mid-term trend line.