How long would you say it would take for someone to complete the quest "Family Crest"?

It all depends on what transport methods are available to you. Assuming you have all items banked, here's a route that will probably work pretty well, starting at Dimentheis:[hide]1) With the fish for Caleb, runes for Falador teleport and Ardougne teleport and a pickaxe in your inventory, cast Camelot teleport and run to Catherby. Hand over the fish and ask about the other brothers.

2) Cast home teleport, run to the Al Kharid mine, talk to Avan, who tells you to talk to Boot the Dwarf. Cast Falador teleport, enter the mine in the north-eastern part of the city and talk to Boot.

3) Cast Ardougne teleport and head to the Witchaven dungeon. Solve the puzzle and mine the gold.

4) Home teleport and run to the Al Kharid bank. Deposit your pickaxe and withdraw a Lumber yard teleport scroll, antipoison, charged Amulet of glory and the rubies and jewellery moulds and make the jewellery. Make them at the furnace, then run north and give them to Avan.

5) Use a Lumber Yard teleport scroll and head to the Jolly Boar Inn. Head upstairs, talk to Johnathon and give him the antipoison.

6) Use the Amulet of glory to teleport to Edgeville. Withdraw whatever you need for the final fight, as well as runes to teleport to Varrock when you're done.

7) Once you've killed the demon, put the pieces back together, teleport to Varrock and talk to Dimentheis.[/hide]There's probably faster routes you can take, but with the proper preparations and by following the steps in this guide, you can easily wrap it up in under 30 minutes.