This answer talks about the 24 hours needed by a wizard to write a spell into a spellbook from a scroll or another spellbook, but I was wondering if that 24 hours needs to be consecutive. It doesn't seem to specifically say, but the requirement being 24 hours seems to imply that it requires a full day.
However, "Note that a wizard does not have to pay these costs in time or gold or the spells she gains for free at each new level. She simply adds these to her spellbook as part of her ongoing research" implies that these spells are written into the book over time, rather than in a consecutive block of 24 hours. Does this mean that spells gained from captured spellbooks and scrolls can also be written into a spellbook over multiple short sessions totalling 24 hours, instead of in a single continuous 24-hour session? Is this specified anywhere?