Is it strongly advised to have an alternate major in a different school than your 1st choice?

I’m going for biochemistry as my 1st choice and general bio as my alt but I’m seeing a couple people suggesting I pick something completely outside letters of science and the respective schools that hold the major.

Not all UC’s even consider your alternate major but if you are applying to a very competitive/impacted major, it is advisable to have a less competitive/non-impacted major as an alternate.

http://admission.universityofcalifornia.edu/counselors/files/freshman-admission-matrix.pdf