Some things about the way I do it:
The ones I solder wires to (I do this at the bench - I never buy the Atlas ones, they are insanely overpriced) are always fresh out of the pack.
For trial fitting of track, I keep a few around with no wires, that have been connected and unconnected several times, so they slode on easily. These are the kind that would be a problem if relied upon to conduct electricity, since they are a loose fit to start with adn any paint used on the rails will surely get down inside. But for frequently connecting track to mark and measure placement, the loose ones are the way to go.
So now that I know where the next piece of track goes - and thus the joiners - I can drill my holes for the feeder wires and stick a pair of wired joiners in place - NOT attached to either the already placed track or the piece I am about to add. THEN I connect the track with the joiners. SO the wires really don;t interfere with anything.
Using flex track, there aren't THAT many joints, even on a bedroom size layout. I do put wired rail joiners on all 3 legs of Atlas turnouts.
Lots of people say this whole thing is unreliabe - especailly with additions like "wait until you paint the rail" or "wait until you ballast" - well, I did both on my last layout and never had the slightest dead spot. All that exposed shiny metal around where the points pivot on Atlas joiners? Yeah, that all got painted so I didn;t have shiny bits standing out. Joiners got painted over, a little extra heavy too, to make sure the paint covered the edges. No loss of power.
I have a hard time trusting things not to move, even when the layout was in occupied living space to temperature and humidty didn;t vary wildly. And it was on extruded foam which isn;t nearly as affected by humidity swings as wood. So I only soldered every OTHER rail joint, and never soldered a joiner to a turnout. Perhaps I'm overly paranoid, but it definitely meant no espansion/contraction issues.
And then there's the layout before the last one, which I did the same thing. However, I test ran the layout by connecting ONE pair of feeders to the DCC system and had no problems anywhere around an 8x12 double track oval. No slowdowns, no power problems of any sort. It just worked. Same organization - every OTHER rail joint soldered, no turnout soldered. Some of the track was painted, but I think by the time it all got done I had run the bus lines and hooked up all the feeders.
--Randy