My dropitis has waxed and waned. There was a period 18 years ago when I seemed to drop everything. Then I got more conscious of the problem and did things more slowly and carefully. Ever since, I've been slower and more careful. Occasionally I do drop things just as you describe, without a warning of weakness. But it's fairly rare now. If, as you say, I tried to multitask and do things fast, I'd have more things on the floor.