How many drives or files you have, whether it's online or local is really secondary. Organization is primary! If you can't locate the files you want in less than 2 minutes you are doing something wrong. And, it does no good to have a file if you can't locate it at all!
Across my HDDs I've got 34,000 personal files, 303,000 images, 127,000 audio files, 3,500 movies and more.
I can locate any one of 80% of those files in less than 20 seconds. The rest I can find in less than a minute.