One of the most important things I ever heard was that 'you can do anything if it's light enough'.
Now personally this has lead me down to the road of (eventually) doing 4 days per week full body routines. However I built up to this very slowly, we're talking years. I'm sure there is an upper limit to volume that an individual can handle, but for now it's going well.
Bear in mind goals too, i'm big enough and strong enough to suit me. My goals now are fitness, health and staying in shape, these are also things to consider while you programme your routine.
What are your goals? If you're looking for size and strength then it's very unlikely you would need a 5-6 day split, a 3 day full body routine would be preferred in my opinion.