I will have to agree that there really is no such thing as "natural". I guess a better term would be, try to not look "obviously unnatural". 10,000 links on Monday, 0 links Tues, Wed, Thurs and Fri looks, to me, unnatural. Every link coming from blog comments only, using the same comment with only one keyword pointing to only your main page I think would look unnatural. So, yes, 10000 one day, 30 the next, etc looks less unnatural. Randomness and diversity will help to not give them the clue that you are the one that is gaming their system. At least try to minimize your Modus Operandi.
Granted, in your link building efforts, not all links are going to stick, and not all links that do will all stick on the same day, so 10000 links will end up being spread out over time. This isn't the worry, though.. the worry is mainly for new sites, or sites that have never gotten many links at all, then suddenly starts to build a ton of links at once.. that's where the sandbox comes in. Google is going to monitor any new activity and see if it is at least somewhat consistent, or if it is a glitch or game.. that's what people mean by being consistent.. once you start, don't stop. And yes, it is going to judge your onsite seo, outlinks, etc. to see if it is garbage, or if it will provide value to their index.
That's where, blasting for pure power and juice, people blast 1000000000 a day to web2.0's without a care, because if those disappear, no loss. If your main site disappears, though, you lose.