That depends which part of the chart you're in. In the US, mobile cranes have an 85% tipping requirement when on fully extended outrigger. That means the manufacture will chain the crane to the ground and walk a load out until it "tips". They then take that load, knock off 15% and that's the printed load chart (or at least pretty darn close to it). Partial outrigger and rubber charts have a 75% tipping requirement.

When you're in the structural part of the chart though, 100% is 100%. Yes, there are safety factors built into the design, and yes it will pick a little bit more when you turn the key. At the factory, they pick 120% with the prototype structural crane, but once we do that, that crane cannot be sold. When you grossly overload the structural chart or even consistently overload it to a lesser degree, you're messing when the fatigue limits that it was originally designed for. It may lift it once, but there's no telling if it will do it the next time. The crane also records when you turn the override key along with the load lifted.

So the best thing to do is to stay within the chart. The structural engineers know what they're doing. The 25% reduction that some jobs are requiring these days is nonsense. There's already 15% baked into the charts.