I tend to think timing is a function of what you are cooking and who you are cooking for. If I am cooking for company, Then I try to adhere to a schedule and have everything done and on the table at the same time. I really hate to sit down to a meal and have it be cool to cold.
Most days there are just two humans to feed in the house. DW and I both get home ar erratic times. Dinner starts getting cooked when we are both together and eaten when it is done.
Actually "The boys" out two labs eat on a very efficient schedule. They have remarkable internal clocks and start lobbying for food at exactly the same time morning and night. Providing someone is there at that time.
Also what is being cooked and experience of the cook is a major factor. If you are cooking something familiarthen you generally "feel" the timing. New dishes tend to go by the recipie, at least in the beginning.
In the final analysis, it is done when it is done. A steak may not always take as long as the last one did, etc.