It all depends on the ficus variety,
@MozBlu. And welcome to NGA/ATP. If you have the benjamina, they can and will drop leaves if you simply look at them the wrong way. Sorry, gals, I wouldn't grow a benjamina if you put a gun to my head.............well maybe, if you cocked it.

All your advice is right-on though. If possible, put it in a tub of water, or better yet, take it outside, and give it a good soaking. If using a hose, do it once every couple of hours for 2-3 doses of heavy watering. In a tub, just let it soak for an hour.
I grow the Fiddle Leaf and the Banana Leaf, and neither one drops leaves. But I am always watering these plants. You say your Ficus is 10 years old. My fiddle leaf is 25+ years old and she hasn't been repotted in probably 8-10 years. I know that she is so root-bound I would have to cut her out of the 24" pot to up-pot. I just water and water and water, most every day in the spring and summer (when she's outside) and every week in the fall and winter (when she's inside).