I have a trusted friend in our local club, we cover each other's tanks when we are on vacation.
The bigger problem for me is the one tank that I maintain. 2 out of my last 3 vacations, there has been a problem. Once when in Orlando, a fish get stuck in the overflow pipe intake for the BeanAnimal 3-pipe system and the OC kicked in and started making it really loud. Worked exactly like it was supposed to, but I had to phone a friend.
Then last week, I was gone Sat-Sun (8 days) and on Wed the 5th after the long weekend, water on the floor...turn out the nut on the bulkhead from sump to return pump got loosened (after 5 years) and decided to drip about 1/2 to 1 gallon of water on the carpet, it was a simple fix but I didn't want him to crank the nut in case it was a cracked bulkhead so I just had him wad up towels under it and change that daily & put a fan on it.