Magic Bullet Looks is a fantastic tool, it is fast when making adjustments and very intuitive on the learning curve. Beware! MBL adds a significant amount of time to your FCP rendering. There is no way around it.
In some of our FCP workflow we would establish the color correction and Look that we wanted, then turn off the MBL filter in each clip until we were ready for the final render. In other workflows, we would do the basic color corrections with the Three-Way in FCP, then export the final edit timeline as a .mov and bring it back in to a different timeline. Then we would apply Looks to the entire clip or slice the clip up into a few sections that would need special treatment.
We’ve since moved over to PremierePro where you can add MBL in an Adjustment Layer and switch the track off/on as needed. Much easier to play with in PP. It still slows down final rendering in PP because it does not use the graphics acceleration card, just the CPU like FCP.
Bars & Tone
SALUTE!