Welcome to the forum @navia2 it’s a great place for advice and support. We were all newbies at one time and we are all still learning and gaining experience from each sit that we do .
“Good enough” is keeping to the frequency that the individual owner has requested and that you have agreed to before the sit starts ( preferably in your discussions before confirming the sit ) .
Every owner is different
It’s not uncommon for an owner to want a daily update with photos . The majority of the 16 THS sits that I have done wanted daily updates with photos but there are a minority that only wanted to hear if there was a problem and would have been irritated by daily updates.
A picture paints a thousand words - a photo (of a dog on their regular walk , cat curled up asleep in their favourite spot or eating their food ) “says” pets are well and being looked after . This means that you don’t need to write a lot of words . Use WhatsApp- take a photo during your normal care of the pets and it won’t take any extra time out of your work day.
Some general advice ( as you asked for it ) Don’t assume what the owner wants about anything to do with the sit - if it’s not already clearly stated in listing or welcome guide -ASK- ( preferably before accepting the sit and definitely before starting the sit ) .
The topic of Frequency of Updates has been discussed on the forum before and you will find reading the replies on this previous thread helpful for your situation.
https://forum.trustedhousesitters.com/t/frequency-of-updates-from-sitter-to-homeowner
You mention a negative review - did they deduct stars overall or just in some categories?
Are you aware of the sitter cleaning checklist ? This is what is expected of sitters Sitter Cleanliness Checklist | TrustedHousesitters.com
When looking at a listing you can look at the reviews that the owners left for previous sitters then you can see if they are especially critical about cleaning ( and avoid those sits )
If this was in other areas of the sit ( not just about updates ) like how often dog should be walked and for how long and where - these are questions to be asked and discussed before agreeing to the sit . If you realise at this stage that it’s not going to be a good match you can withdraw your application .
As sitters we can do much to ensure good communication from the outset before confirming the sit If the owner doesn’t answer questions about how often their pet needs walking / for how long ? or how long they can be left alone for - that is a red flag 
an indication that they know that they have unreasonable expectations and want to wait until you get to the sit to reveal these responsibilities.
You can’t change the review that the owner has left but you can reply to it .