Plane Sailing, this has been debated many a time around here. The general consensus is that scribing a scroll takes one day per spell, regardless of whether that spell is 1st level or 4th level (higher than 4th level and it pushes the cost over 1,000gp which increases it to multiple days).
According to the rules gurus here, you cannot circumvent this by putting multiple spells on a single scroll.
However, we have a house rule that you can scribe a number of spell levels in a day equal to your Int bonus, so long as the gp value does not exceed 1,000gp. I should note that we have a few other minor house rules with regards to wizards and item creation that serve to keep them from being regarded as too powerful.