Competent cooks are always thinking cooks, David.
It’s been my experience that a few degrees don’t much matter to the outcome with meat and poultry. However, cooking time can matter with tender items over about 4 hours in cumulative cooking time, - and of course with seafood that’s easily overcooked in much shorter times.
One of Harold McGee’s books would be one trusted resource to learn more. The Journal of Meat Sciences has had a few informative items over the years too. And if you enjoy quadratic equations, Douglas Baldwin, now PhD, provides formulae to calculate tenderness.
Also, Baldwin cites the following:
P. E. Bouton and P. V. Harris. Changes in the tenderness of meat cooked at 50–65°C. Journal of Food Science, 46:475–478, 1981.
You may find keeping a cooking journal in which you record the details of each event along with your sensory perception notes will lead you to discover what’s best for you, - and replicate it ongoingly.
Happy cooking and stay safe.