I have said earlier that I wanted to start training multiple times a day, in line with the notion that the more you practice something, the better you get. I changed my approach again a little while ago and have reduced the amount of time I am putting into the perfect pitch training. At this point, I am training 15-20 minutes one day, then usually having two days without training, then another day of 15-20. I am finding that this is enough to keep my ear at the level it is - actually enough to keep improving it. Part of my reason for changing the routine is simply because I want to spend more time improving other areas of my playing such as jazz improvisation, comping, etc. Also, at some point, I'd like to get better with relative pitch.
I think that it is good to work on perfect pitch training every day for a while, but at some point switching to every other day could be just as beneficial. After doing it for a really long time (in my case, over 10 years), I think every few days is sufficient.
