What do you mean? Burn Notice typically has two plots running at once (the plot that advances the overall story arc, and then the per-episode plot where they help someone), and they like to switch back and forth between the plots frequently, but they never show them at the same time.
Lately they've used split-screen to show simultaneous actions by different people. It works rather well, because while the videos show different actions, they both fit into the same coordinated plan.
For a few seconds at a time, during transitions between scenes or in the lead up to advert breaks. Synchronicity of relevant actions is minimum - ie a car driving, while someone sits in a room. the other two may be 2 sides of the same phone call.
There's not really ever 2 concurrent plots happening simultaneously.
