So to take it a step further let's look at some of the stacking people do on the private servers and intend to do on the live game.
- Rallying Cry of the Dragonslayer +10% Spell Crit, +5% Melee/Ranged Crit, +140 AP – 120 min
- Songflower Serenade +15 all stats, +5% Spell/Melee/Ranged Crit – 60 min
- Resist Fire +83 Fire Resistance – 60 min
- Warchief's Blessing +300 HP, +15% Melee Haste, +10 MP5 – 60 min (Horde only)
- DM North Buffs (DM Tribute) +15% Max HP, +200 AP, +3% Spell Crit – 120 min (Patch 1.3)
- Sayge’s Fortunes (Darkmoon Faire) Choose between +10% Damage/+10% Agi, Int, Spirit, Stam or Str/+10% armor/+25 magic resist – 120 min (Patch 1.6)
- Spirit of Zandalar +10% Movement Speed, +15% Stats – 120 min (Patch 1.7 – Persists through death up until patch 1.11)
- Lordaeron's Blessing Effect (DND) +5% Max HP -30 min (Patch 1.11)
- Traces of Silithyst +5% Damage 30 min (Patch 1.12)
These are just possible world buffs on top of your normal class buffs and consumables. It is not uncommon for groups to stack as many of the above buffs and get to the raid instance and log out just to keep the timers. It is also one of the reasons fury warriors are so strong is due to the way they scale.
Take a look at the list below to get an idea of the consumables you should bring if you want to min/max.
Comprehensive Classic WoW Consumables List
Then it just keeps going. If you are going to be useful to your raid and min/mix there are tons of potions buffs and other items you will need to get which pretty much all but flasks are wiped upon death. So having everything from potions, food buffs, whiper root tubers, engineering items, the list goes on and on.
Then you get to the point of how much mix, max do you want to go. There absolutely will be split runs of content such as MC with a mix of peoples alts and mains. Running MC, Ony 4-5 times a week funneling peoples mains through for gear.
Then we have the PVP grind pushing Rank 14's through week after week running 12+ hour days or even more likely account sharing by some. Because make no mistake the Rank 14 gear is better than BWL gear in many cases.
These are just some examples of what to expect out of the ultra hard core guilds going into Classic. What level of prep is reasonable and what is too much? This is actually a decent question I would be interested in your guys thoughts.
Also don't forget that classic is a game beyond just raiding in no small part because of consumables and prepping the best you can before you even step foot in a raid.