1 - There is no ‘quality’ requirement for observations on iNaturalist. As long as it is a real observation, it is valid. To achieve research grade status, it requires certain parameters (media, date and location).
2 - As long as they are unique individuals (or the same individual at a different time and or place), If someone wants to take the time to document each separate tree in a woodlot, they are fully within the rules and guidelines of the site to do it.
3 - There is no limit to the number of observations a user can submit.
If you feel any or all the above should be changed, then I would suggest adding a feature request that covers your idea.