Cleaning up paths in AI

In Illustrator CC 2017 you could use the Join tool: Join tool « Adobe Illustrator blog It takes care of too long as well as too short paths.

But it's not automatic.

i would recomend Adobe Illustrator plug-ins to speed up workflow from Astute Graphics

it would give you the tools to fix quickly

but does cost. not much.

another option could be to make sure all lines are too long. and not too short. then select the lot and use a boolean operation to split it up.

have a play with the pathfinder tools.

Gratefully Dyed,

Those going farther are quite sumple, Smart Guides being your friends: you may select the longer path and hover round over the intersection and Click when Smart Guides say path, then delete the outside snippet.

When you are close and if you can live with (almost) unseeable changes, those falling short can also be simple: with the shorter path deselected, you may ClickDrag the short Anchor Point outwards in the right direction with the Direct Selection Tool Smart Guides say path, that will simply stretch the path (segment) without changing the Handle Length; if desired, you can adjust that (still with the Direct Selection Tool), as you always can.

To maybe minimize the need for corrections, you may set the Stroke to Round Cap (which corresponds to Round Join) instead of Butt Cap.

Edit: What Doug said, of course; unless that disrupts your going fast.

Hi Doug. No more short winters within this drawn out autumn spring, I am afraid; and maybe none at all for you.

use smart guides as you draw (View > Smart Guides). it'll be much easier to have your paths terminate at their intersections: