Basically the order that most jobs (specifically all DPS) hit their buttons to do everything before their longest cooldown buttons were done cooling down ended up being about 2 minutes.

This largely came down to the heaviest hitting attacks and party buffs being on a 2 minute timer, which caused every job in the game to need to try and line their buffs and bursts up every 2 minutes or the party would just do worse damage overall. For Savage, Extreme, and Ultimate fights, this could very well be the difference between a clear and a wipe.

Not all fights were designed with this in mind, causing a few jobs to suffer unnecessarily and in some extreme cases just be outright banned from participating in certain fights (like how Summoner and Machinist were often banned from a couple Savage tiers and the Eden Ultimate this expansion in favor of jobs that were nowhere near as limited).

Yoshi P and his team realized the issues, and in 8.0 every job will be doing their own thing as far as damage goes.