Helper engines

I posed the following question down the street in the saloon, and we've been kicking it around for a day or 2. Now I'd like some more input.
Here's the question:
What was the advantage of runnin a helper mid train, or on the rear, rather than breaking the train into 2 sections and running a second section, and then reassembling the train at the top of the hill?
I got to thinkin' about this the other night. If an engine was cut in mid train on the way up the hill, then it had to be cut out and the train reassembled, the same train could've run as 2 sections to the top of the hill and then reassemble the train and it could've continued on as originally scheduled, sending the helper back down the hill.
I've figured out that as a second section you would've had to have a complete crew and bobber, but what if you didn't need a full crew?