For really slow engines, like ion propulsion, add a helpful option (may be hidden with a tick button or whatever) to change one-burn planner to multiple ones.

How to schedule them:

1. If the burn takes place in distant future (eg more orbits then requested N), than just split it back in time:
   1.1. Add maneuver node one orb. back
   1.2. Split ΔV in (N-1)/N for new node, 1/N for old (futurer) one
   1.3. Perform the same procedure for the new node with N-1 until N = 1
2. If the burn scheduled to the nearest time:
   2.1. Add maneuver node further in the future, to one orb.
   2.2. Split ΔV in 1/N for nearest and (N-1)/N for further node
   2.3. Perform these steps for the last node with N-- while N>1
3. If the burn must end in less then requested orbits, show a warning.
4. When performing the maneuvers recalculate and adjust the scheduled maneuvers to get the desired trajectory.

Also maybe add automatic orbit number planner somehow.

Also a good option is to add some nonlinearity for splitting, to save time, eg, have more ΔV in the further burns, or maybe better to do other way?

A mod called, surprisingly, Maneuver Node Splitter, handles this just as well.
http://forum.kerbalspaceprogram.com/index.php?/topic/132209-11-maneuver-node-splitter-v150/#comment-2412017

A mod called, surprisingly, Maneuver Node Splitter, handles this just as well.
http://forum.kerbalspaceprogram.com/index.php?/topic/132209-11-maneuver-node-splitter-v150/#comment-2412017

Sorry to dig up this old issue, but as the mod mentioned above is discontinued. So, can we have this node-splitting feature in future MechJeb releases?