It's really up to a designer of a project to always select components, modules, and power sources such that they are not operating close to their 100% ratings. I would never select power components that had to operate closer then say 75-80% of their maximum rating to allow for some 'headroom' and possible future increase loads. Device maximum specifications are almost always stated optimistically and assume some conditions that don't always reflect most normal application variations like ambient temperature changes, input voltage variation, and heatsink requirements. Even with simple components one wouldn't install a 2 watt resistor that has to actually operate at 2 watts of heat dissipation. With experience comes the wisdom of how conservative one should be for selecting components in a specific project or design.
Lefty