I have an i7 and it’s possible to build large scenes with high quality in under 10 minutes if you just optimize your lightmap resolutions and general lighting situation. For daytime outdoor levels, if you have more than one sunlight and one skylight, something’s wrong. Landscape does not need the highest resolution lighting if it’s very smooth. While AO baking will definitely require higher res lightmaps, you can typically save a lot of space by lowering the lightmap resolution of objects in shadow. If you have a chandelier casting light, you can make each bulb dynamic and use a single generic static light to calculate bounce. This would be much cheaper than a stationary solution (which would have serious trouble with overlapping) and would look much better than a static solution by itself.
People should know the limits of lightmass going in, though. While you CAN use it to cast gorgeous stained glass lighting on the environment, you CAN’T just crank up the resolution of a massive project with thousands of meshes, build on one CPU with less than 8 GB of memory, and expect a quick and easy build.