Two more things that will help you set yourself and others tasks correctly.
3. Are you able to complete this task in 15-30 minutes with a relaxed brain?
Bad: "Read War and Peace," "Mortgage."
Okay: "Read Chapter 1, War and Peace," "Call the bank, ask for a contract."
Tip: Big tasks are almost never done in their entirety, so it is either impossible to predict the deadline, or more urgent cases appear, or distract (we are not robots).
Now about how sensibly the date of the task has been set:
4. If an execution date has been set, is it dictated by a real necessity?
Bad: the task was given a deadline, because otherwise you will never do it at all.
Good: Periodical tasks or tasks are linked to dates, the execution of which on other dates has inevitable negative consequences ("Make a loan payment", "Send weekly report", "Review task list").
Tip: The situation where a task requires a date to be assigned usually indicates an overall overload. In this case, you need to think about the shoving law: "When you try to shov the one that is not shoved in, it is shoved in earlier" and think about what is shoved in earlier?