Showering once per month is OK as long as you're not really dirty or sweating a lot.
if you get dirty a lot or sweat a lot then you should shower at least once a week or more.
But if you're sweating or you don't get all that dirty then showering once per month is OK.
There have been times I've went a month without showering and I've been OK.
If you can you should at least take a sponge bath with a rag and some soap to wash off some of the grime that you may not see.
Also note that even though you may not be able to smell your own body odor some other person might.
So if you don's shower often you should use some deodorant if you're gonna be around people.
But if you're going to work around people or be around people it's best to shower everyday or every other day.
Showering too often can dry out your skin and strip your skin of the natural oils.
So it's good to skip a few days between showers or bathing.