These are best used sparingly. I put 2 or 4 bulbs in my Whirlwind in the very back corners. These were the "quick changing" not fade between color lights. The end result and covered up one of the 4 colors so the bulbs periodically went dark. The end result was a subtle flashing effect in that area. The strip light I put above it overpowered the effect a little, but I thought it looked very cool and was a cheap mod.
The 20 to 40 second mark of this video (not made for the purpose) shows the effect.
Totally worth $4.