I never really found the tracker particular helpful to be honest.
I've been having a pretty good time of this. In particular where gyms are concerned. The gym near my home (like a block away) is controlled by my team, Mystic. The other day I went up there and trained it up from a 6 to a 7 and popped a 900+ CP Hypno in there. Been through two 21-hour cycles now, occasionally re-visiting the gym to bring their prestige up when others take cracks at it. Training has been hugely helpful for me, in being able to know on the fly which of my Pok?mons will do better against which other kinds, and in learning to dodge better (which I'm still not very good at).
I guess part of what helps is that my gym is an ugly-ass church in an ugly-ass boring neighbourhood. Try adding a Pok?mon to a wildly popular tourist spot, like Harpa Concert Hall, and you're lucky to have a Pok?mon in that gym for an hour before some whale rolls up and mows everyone down with their 2000+ CP Snorlax or whatever.