How many points you get is really a large variable? First, what is your major bucket? Do you have any negatives or a thin file? You said your util was always low, but how low? What was both your card utilization ratio and total ratio before you paid this down? If you jump (drop) several categories, it will boost your score more than if you only jump (or go down) one.
Will other facts change when you get your next report (inquiries falling off into the next lower set, or AAoA or LOC going up into the next set etc.)? The best way to get a ballpark picture of this is to check your myFICO 3B “scores” section. Scroll down to the FICO® SCORE 8 INGREDIENTS section toward the bottom for each CRA. Look at the 5 categories and see what they are (Exceptional, Good, Fair, etc.). Anything that is NOT Exceptional open it and see what you have. For example, if your LOC is good and you have 2 years 1 month, that will not change a score by going to 2 years 2 months; HOWEVER, if it is fair and you have 1 year 11 months, that will change your score and give you a boost next month. The later means your boost will not simply be because of your CC util going down, but also because your LOC went into the next subset.
Also, be aware your score could go DOWN. For example, did you close an account long ago and forgot about it. Maybe you paid off a mortgage, car or personal loan. If it crosses that 10 year mark all kinds of bells and whistles could go off (AAoA for one) if it were a good account. Also check on old, closed CCs.
You will see all kinds of values listed by the community for dropping below 8.9% and each is valid; but, you must consider whether the poster has considered all the nearly constantly changing variables that go into making a credit score and giving them the boost or drop. It is said that your score is nothing but a snapshot in time, and that is true. Why? Well think of taking a picture of a passing airplane on a cloudy, windy day. Not only will the airplane be in a different position seconds after you took the photo; but also the trees, clouds, and any other background scenery will be different after you snap that shot.
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PS "IF it looks good to lenders, I'll take it anyway." What Lenders? The boost you get will, most likely, be different for each FICO score model you have.