You can expect a clear time of 9 minutes with this setup. Agility and Astrology will greatly increase your clear speeds.
Check your own setup with Can I Idle or Combat Simulator to see if you meet the HP requirements. If you're following this setup exactly, you'll need Level 86 to idle.
If you have FEZ then use it, but it's not mandatory to have it.
Because later monsters in the dungeon are quite evasive, Ancient Crossbow boosts the clear time by a significant amount because it lowers the enemy's evasion until the end of the fight.
Scaled Shield is important because the poison damages in percentage, meaning that Glacia will suffer. A lot.
With Scaled Shield, you will clear the dungeon at least 10% faster when compared to its unupgraded version, (U) Ancient D-hide Shield.
Use the top two prayers for accuracy or max hit, depending on your situation. Check with Combat Simulator to see which is better for your clear time.
Late-game Idle builds
The remainder of this guide assumes main game only, and does not consider any of the late-game armour and weapons that are available.
The rest of this guide is intended for use after 100+ clears using the build shown above. The goal of this section of the guide is to maximize scrolls and to help farm for any missing items. It is assumed that you are level 99 in all skills with access to all of the weapons and items in the main game, and access to all DR and HP pets. This assumes you are (unless otherwise noted) using a Agility setup optimized for combat, are using your best prayers, your best summoning synergy, and are using Diamond Luck Potions.
Ranged
This build farms around 17 to 18 scrolls/hour, depending on your Astrology bonuses. The Cape of Prat is marginally faster at clearing dungeons than the Maximum Skillcape, but it will also doubles your ammo consumption.
This build farms around 19 to 20 scrolls/hour, depending on your Astrology bonuses. To use this method, you need to have 1090 HP and 57% DR. This is achieved by using Rocky Waters instead of Lake Swim.
The overall time for this build is likely to take longer than setting up ranged because of how many runes you will need. This build relies on the Shield of Magic Power to survive, and also keep a high dps. Overall, it is less effective than the ranged counterpart, and might lower the number of scrolls/hour as a result.