I think the definition is necessarily vague, because it comes down to common sense (which varies widely from one type of organism or situation to another) and how you use iNaturalist (which varies from user to user).
If I observe a bee for one minute visiting three different species of flowers, it seems to me not unreasonable to submit it as three observations, even though I know it is one individual at times/locations that are separated by just a few seconds/centimetres. “Bee feeding on rose” and “bee feeding on daisy” are two separate pieces of observed behaviour that are scientifically interesting, and which it could be most useful to keep separate. But if I take 10 photos of one bee over 10 minutes as it buzzes aimlessly around my garden, it may be worthwhile submitting all 10 photos (if they show different angles, for instance) but most logical to treat those 10 minutes as a single time and the whole garden as a single location.
What constitutes a different “time” is just as undefinable as what constitutes a different “location”. If I photograph the oak tree outside my house at 8am, chances are it will still be there at 9am, and again at 10am, and it benefits nobody to spam iNaturalist with hourly photos of the same tree. Monthly photos, on the other hand, could show it in different stages of leaf and flower, which is scientifically interesting information. But other organisms live life at an entirely different pace: a little toadstool might emerge, open up, release spores, and collapse over the course of a day or two, and documenting each stage of that is scientifically interesting.
This kind of information would be invaluable to people studying the flower choices of bees or variations in the date that oak trees lose their leaves from one year to the next, but of no interest whatsoever to people who use iNaturalist to compile a species list for their garden/trip/life. The latter type of person, once they have logged one feral pigeon may have no interest in ever logging another.
So I think the answer is just to try to understand the ways in which iNaturalist is useful as a scientific tool. Once you have logged a photo of a common daisy in your garden, you may not see any point in logging more. But to a person studying the number of petals on daisy flowers, the more photos of different daisies they can see, the better, and it would be most helpful if each plant is submitted as a separate observation.