Like daily = every day and monthly = every month, does decadally = every ten days exist?
There is no single word or phrase that means "every ten days", unless you want to get picturesque and primitive and say something like "every two hands of days". Also remember that you want to use a common phrase that everyone will immediately recognize, so "every 10 days" is your best bet.
But that doesn't apply to all time periods. For fun here is a list of the names of various lengths of time, although it doesn't include compound terms like "bi-weekly" or "every other year", and a few others like "sesquicentennial" (150-year anniversary of something).