Pretty much all the top guilds go for the "lets raid as much as we can and have as many attempts as possible!" approach, and it does work in some respects, you do the fight so many times that you dont even have to think about what you're doing anymore, you just do it automatically. I remember in wrath though when people were working on LK 25 hc, all the guilds who killed it raided loads and wiped god knows how many times which showed they valued quantity over quality (what i mean is rather than giving it a break, they would headbash it for aaages), then there was this guild called minions of mithril who ranked 57 and raided 3 days a week for like ~10 hours, massive respect right there. I believe raid quality wise, they were one of the best guilds around because i doubt a lot of the top guilds would have killed the boss as quick as they did with that raiding schedule.
Bosses get quite easier when information/vids are released. Or if you farm gear before going for them. Personally my guild killed Morchok in a few pulls and Yorsahj in under an 1.30 worth of pulls. However, have a good 30+ on warlord atm. Just tweak strategies and setups if needed and keep refining and a kill might be quick!
Strats evolved by wiping, although we had normal modes 'solved' on the ptr.
Warmaster is the first fight where we were not making constant progress and fine tuning to increase chances of a killshot, it has seemed to be 'wipe till people learn better'.