I should have voted for every other week. I have four bikes. I get confused as to when I did what to which. My favorite road bike, probably does get bi-monthly.
I do have a Park Chain cleaner. makes it so easy. Should do it weekly. Here we get no rain 9 months. I use White LIghtening or some other equilalant, so drive train does not get too awful.
Not satisified with just chain cleaning tool. When I attack dirty chain I do the whole drive train. Use brush, citrus cleaner and get up in cogs and chainrings. Makes me feel good about my bikes to look at the whole drive train and it is a shiny silver color. No junk.