It really does boil down to how much writing you're willing to do.
The more possibilities there are, the more likely someone will spend more time playing your game, and the more they'll be willing to replay it in hope of finding a different path after reaching an ending.
On the other hand, too many endings quickly becomes unmanageable, both to write and to script without getting pages mixed up or accidentally causing bugs and dead ends.
Pick a manageable amount of endings, somewhere between 2 and 10, and go from there. Plot some side routes, but ultimately, funnel everything back towards those set endings. Having certain checkpoints that the reader must pass through helps too, because it prunes back the amount of branches, while still giving some leeway in how the reader gets from point A to point B.
Another possibility is to write 'dead ends' that don't immediately end, but allow the reader to progress another two or three pages onwards, possibly with some more branches that lead back to the main path or into other dead ends. That helps give the reader a feeling of choice without having to commit to writing a whole new path just to accommodate it. For instance, write a few choices that, if chosen, will ultimately result in game over no matter what, but this doesn't become apparent until three or four more choices down the road.