Even if you get the rest right, unless the tree receives assistance whilst establishing.
Establishment is the period during which the tree expands it's root system, it is established when it has a "natural" root system (trees are planted with a small diameter nursery root system) and can look after itself without the need for assistance.
During this period of deficit (when the root system is still expanding to a natural tree) the tree will need help. This assistance is primarily watering (mulching; potential pruning, adjusting / removal of guying/staking also are needed). Feeding is usually unwarranted as the soil if healthy should provide all that is required.
This period of deficit / establishment can last upto 5 years. The idea of 12 months aftercare to ensure establishment is utter nonsense.
The people that specify planting projects and those such as planners who pass them have to ensure that the resources are in place for competent aftercare for 5 years. To provide 5 years aftercare will guarantee the proposed landscape after 5 years. How many new landscape schemes do you see with dead trees, leaning trees, trees with epicormic/basal growth, stressed trees (read trees as trees and shrubs)?
There is a British Standard that specifies 5 years aftercare (along with right tree/right place/planting correctly) BS8545:2014. If only Local Authority planners specified this as a condition.
For all planting the budget cannot just be spent on the trees and planting, it is better to plant less and provide a budget for sensible aftercare program.