I almost always search in Vim with /, and then continue searching forwards with n and backwards with N. Sometimes, however, I use ?<
/
n
N
?<
That is just the way it is, notwithstanding some debate on the developers' mailing list ...
Here's what you can do about it:
:noremap n / :noremap N ?
Relevant mailing list thread with a lot more interesting info: https://groups.google.com/d/msg/vim_dev/8jSoA931P2Y/JklYtxFOiAYJ