How much time is "enough time" for a task?

Your task gets completed at any time duration you allocate. If you allocate too much time to it, you end up doing unnecessary tinkering & tweaking to the task (over-perfecting) until the time allocated gets over. On the other hand, regardless of how much shorter the time is allocated for a task, it gets over within that.

Parkinson’s Law

Work expands to fill the time allotted for its completion

Too much time = wasted time and effort;

Too less time = ending up in frustration;

There’s a sweet spot between them, where you can have a deliverable ( a completed task ) that has only essentials but is not perfect or polished.

That is, time and effort are utilized well.