PED,I think you are on the right track (sorry) putting them in relation to the number of joins rather than distance. I have a small layout using the smallest radius curves and lots of short tracks and have done what you proposed. Whilst the layout is still new, I haven't had any problems yet. I soldered wires to the rails as well as using the Kato powerfeed tracks where they fit my design.
Alan Jones in Sunny Queensland (Oz)
My previous layouts (all HO & DC) were always built with flextrack with minimal rail joiners (mosty soldered) so I could be be reasonable generous on spacing of rail feeders. However, I am now building a new N scale layout using Kato Unitrack (no soldered rail joints). Most guidance I find on the internet is very variable with ranges from 3 feet to 6 feet apart for traditional track with little info on spacing for Unitrack. I don't think distance is the main factor with Unitrack. I think the number of unsoldered rail joiners is more critical than just distance since the major losses are at the rail joiners. Power drop in a 4 foot section of track would be much higher if it was built with a bunch of short segments (many rail joiners) rather than fewer long track segments (few rail joiners). I have not tested this but logic tells me this is the case so I plan to always use the longest possible track pieces to minmize rail joints.
For track feeders, I plan to use the Kato terminal rail joiner (power feeds thru a rail joiner) or my own home made version of the Kato joiner to save a few dollars. My main question is how often should I include a powered rail feeder in my Unitrack layout? My current thinking is to insert enough power feeders such that no spot on the track is ever more than 4 or 5 rail joints away from a feeder. That means inserting a track feeder midpoint of every 8 or 10 joints of track. In addition, I will be using a track feeded at the points end of every turnout to minimize any power problems thru the turnout.
I am looking for some feedback from Unitrack users on what spacing they found to be best.
Paul D
N scale Washita and Santa Fe RailroadSouthern Oklahoma circa late 70's