Yes...
Odorlos is not "self renewing" like live bacteria, it exhausts itself in an average of about 5 days...faster in hotter weather. So you may even need to add it every couple of days that you're aboard and using the system....you'll just have to play it by ear.
The time to add more is when you START to notice odor out the vent...don't wait till it gets bad. As long as there isn't any, it's fine. So pay attention and you'll learn how often you'll have add for YOUR use of the system. However, regardless of the weather, if you pump out and add last thing before leaving the boat to sit, you'll need to add more with the first flush when you return...'cuz it'll exhaust itself pretty quickly with almost nothing in the tank.