soldering ?

I have a simple soldering question. I have a 12020 controller that has double wires for each connection. My soldering skills are basic, and I think it may be a weak link. Set up E-Maxx 12020/Feigao 7XL/ 14T pinion / 51T spur / stock diffs. I am finding that the motor skips at full throttle. I am suspecting it's the soldering.

1. Deans connectors - I twisted the two wires together annd soldered directly to the connector. A huge clump of wires to the little connector. WOuld it be better to solder a short single deans battery wire to the connector and then twist the other end to the two 12020 wires and solder?

2. Connecting to the motor. The wires on the motor are presoldered. I tristed the two 12020 wires together soldered them and then soldered the motor wire onto it. Would it be better to "sandwich" the motor line between the controllers and then solder?

Thanks!