I also find deodorant to be useless.

I can anecdotally attest to my own strategy. I buy rubbing alcohol. Have a shower, clean the problem areas. Shortly after I get out I apply the alcohol to my arm pits, and if I think I'm going to really be sweating I spray some over my upper back, chest etc. Nothing close to the amount one would use if they were spraying deodorant. The result is that I can go several days without any bad odor, even when I sweat so much that my shirts are saturated, they don't even smell, to me or anyone else.

The side effect of doing this is that I am far more sensitive to perfumes and deodorants people use, and they just aren't at all pleasant in the quantities people feel they need to use to smell "nice".