Shooting real estate interiors and exteriors on a regular basis, I thought I'd post some work demonstrating natural light vs. strobes. For interior work, I always use strobes...and can't think of an exception where I haven't. Strobes or speed lights just give it that extra pop that draws your attention to the room. I usually only use a single YN 560 III wireless speed light to light up an area. The exception would be in the case of the photo displayed of a very large room where I used 3 (actually just one moved around 3 times) since this is a composite image made up of 4 images. The speed light was in the upstairs and then 3 spots in the downstairs...the 4th image was an underexposed shot just for the window. I merged all 4 images in photoshop to produce this final result.
As for the outside image....100% natural light with some shadows and highlights managed in LR. Had I done this one at night, I would have again done a composite image and moved my single speed light around the pool area to light up every little plant and detail.