Total time to copy a spell from a spellbook?

Question

In order to copy a spell into a spellbook the PHB states:

A wizard can also add a spell to her book whenever she encounters one on a magic scroll or in another wizard’s spellbook. No matter what the spell’s source, the wizard must first decipher the magical writing (see Arcane Magical Writings, above). Next, she must spend a day studying the spell. At the end of the day, she must make a Spellcraft check (DC 15 + spell’s level)...

...If the check succeeds, the wizard understands the spell and can copy it into her spellbook (see Writing a New Spell into a Spellbook, below).

This segment states:

Writing a New Spell into a Spellbook Once a wizard understands a new spell, she can record it into her spellbook.

Time: The process takes 24 hours, regardless of the spell’s level.

So how long really does it take to copy a spell? A whole 48 hours of uninterrupted study? Without sleep? Or is the book simply suggesting the character spends their normal 8hr adventuring day studying and copying the scroll? The reason I ask is doing something like crafting a magic item clearly defines how long the spellcaster must work during the day:

The caster works for 8 hours each day. He cannot rush the process by working longer each day. But the days need not be consecutive, and the caster can use the rest of his time as he sees fit.

For things like scribing a scroll the book indicates it takes "one day" and does not specify hours. This is why the "24hr" phrasing gives me pause.

Answer 1

32 hours, six seconds

Given the time scales involved, requiring hours or days of study and work, it has to be assumed that, generally, you're scribing new spells in your downtime. In that case, the difference between a day and 24 hours is irrelevant.

However, this is not necessarily the case. Tome and Blood introduces a portable writing desk, and nothing specifically says you need peace and quiet, or rest, or an uninterrupted period of time to scribe a spellbook.

Step 1: Decipher the magical writing

According to the Spellcraft skill entry (PHB p.82), this takes a full-round action.

Step 2: Spend a day studying the spell

This takes 8 hours according to the Spellcraft skill entry. This means that "a day" in this case refers to a working day of 8 hours.

Step 3: Scribe the spell into your spellbook

This takes 24 hours. Taken literally, this means three 8-hour working days, even though I suspect the author may have meant one working day. The FAQ is silent on this and the Rules Compendium repeats "24 hours". We must therefore conclude that, unless the DM rules otherwise, it literally takes 24 hours of total work.

Nothing says that work has to be contiguous, or that the wizard needs peace and quiet, so he could of course bring his portable writing desk into a dungeon and scribe a few hours at a time between encounters. Nor does he need to be well-rested, so he can, by the rules, pull an all-nighter and get his spellbook written in one day.