Why is the volitional form used in this title 「時には自分を疑おう」?

I have always struggled to understand the volitional form and translating into English.

From a videogame guide I am going through, translating, I have this title:

時には自分を疑おう

”疑う” meaning "to doubt / mistrust". The meaning of the title is surely not "let's doubt ourselves" but probably more like "doubting yourself..."

But then why is the title not 「時には自分を疑います」 ?

For context, here's the start of the body

ある謎にぶつかり、解決方法がひらめく。　ところが　実際にやってみるとうまくいかない。

Answer

時には自分を疑います

would mean something like "From time to time, we find that we doubt ourselves". The intended meaning here, I think, is that we should doubt ourselves. Something like

時には自分を疑おう
At times we should doubt ourselves

which comes from "let's doubt ourselves from time to time", but "let's" sounds kind of strange in English.

You've told us nothing about the video game, so I don't know whether that makes sense. Probably it doesn't make much sense for a car racing game.

For the Legend of Zelda games, this does make some sense. The start of the body copy you added says that, even when you think you've figured it out, you might try your idea and find that it doesn't work as well as you thought. So "From time to time you should doubt yourself".