Thank you for reading and commenting!
It all depends on what you want to achieve with your writing. If you just want to write for yourself without writing a book or having a blog that people read then, of course; writing once a week or once a month absolutely cool. You may have great results whatever that may be. It will also be a slow process in getting your goals if you have any.
However, if you want to get better and better at writing you have to write and the more you write the better you’ll become. Your writing changes the more you write! :) It’s like exercising a muscle the more you exercise the more lean you become so is the writing.
Of course, no-one should feel bad if you only write once a week or once a month it all depends on what you want to achieve. It’s by no means everyone should do it, people should do it if they feel inclined to. ;)