Run-in is very important and is the fact because the engine you purchase from any Shop are not the best fit, not like a special prepared engine from the factory. Only a few in the world have this opportunity to have factory prepared engine.
To get the max out of your purchased engine, no matter $500 to $5000, you will need some form of run-in. The run-in procedure , if you know what to do, will help bring all the componments of the engine into harmony so they work efficiently and effectively therefore your engine will be more powerful and last longer.