Just want to point out the flip side of this: ~85% of first-time undergrads graduating in <=4 years means 15% are not. And ~75% of transfers graduating in <= 2 years means 25% are not. So basically, odd are very likely you know at least a couple people in either of these boats.
Personally, I know that taking 1 extra quarter is quite common. Same with graduating 2 quarters early. Fall graduating is a fact of life, wherever you are on the spectrum.
Just pointing this out to show that it is totally okay normal for students to take longer (or shorter) than 4 years to graduate. College isn’t one size fit all.