Have 2 x 2080s and have opened them only twice in the past 4 years.
Good for lazy bums like me.
Actually the flow indicators on the filter are best way to decide if any cleaning is required.
I just did clean job on my Fluval FX5 this past weekend and it was running for 5months straight with 50% w/c every week. My flow was great but the impeller was making Noise so clean it and clean the media and now I will go another 5months before I clean it. Good luck!