If I am looking for something specific like a new suit, dress for a wedding, something like that, I want a friend to go with me so they can tell me how it looks.....they either come with me or deal with the barrage of text pictures of me in different outfits.

But, if I need to supplement my wardrobe, I like to go it alone.
If I am just out to relax and not have an agenda in mind, I want a friend to go....that's more of a social outing for me and I rarely buy anything significant when I do that.
For the grocery, I want to go alone.