I realize that, and kinda prefer it to do the "make up an ending".
Then maybe later they do a re-do version like Hellsing Ultimate & Fullmetal Alchemist Brotherhood.
Of course it really doesn't help matters if the people doing the manga take a long time to release new chapters/volumes.
Plus sometimes they never seem to find a good place to call it quits.
Then there's the people who get brought back into a world they left years ago to do some new "retro" chapter (Love Hina & DBZ).
Toho's Godzilla Will Live Forever!