What kind of days? The Bible in the same place refers to all 6 days as "the day" which means according to the Bible a "day" can at least equal all of the first 6 days. Seems to me that the Bible itself suggests "day" means something different than just 24 hour periods here, or that perhaps time is relative and so 6 days can mean just one day depending on one's perspective, and who knows what 6 days or one day is to God.
Genesis 2:4 "These are the generations of the heavens and of the earth when they were created, in the day that the LORD GOD made the earth and the heavens."
The whole creation period is referred as "the day."
It still indicates a much more varied use of "day" than you seem to be willing to admit to. If "day" can mean "when", then each "day" imo of the creation week can just mean "the when" these things occurred. The fact the earth wasn't even created until the 3rd day, nor the sun until the 4th, strongly suggests to me, and to plenty of others such as Jewish scholars (long before the evo/creo debate I might add), that the days here are not our days, as in 24 hour periods.