Hi Janine, I am assuming that you are referring to different simulation platforms (like virtual-prototype, RTL simulator or emulators like Palladium) when you use the word "environment". These platforms provide different levels of observability and simulation-performance (sim-performance) throughput. For example: RTL simulators give better observability but low sim-performance while emulators give marginal observability but deliver on sim-performance. Depending upon the verification stage, platforms are chosen, for example initially RTL simulator is chosen as the scenarios one would run are simple and the expectation is more bugs will be flushed out at this stage. But when confidence on RTL is built, folks take it to emulation or Sim-accelerators for stress testing and benchmarking. Presently emulation vendors are improving observability and investing on transactional VIPs (partly synthesize-able) to re-use test-bench. My take, emulation platform may be the way to go but bottlenecks like compilation, cost etc will have to be addressed before it is adopted widely.