In PTTP, it is recommended that you pick 2 exercises(i.e. Press, DL, Bench...) and perform 2 work sets 5 days a week. GTG is working on (i.e. pull-ups, pistols...), frequently throughout the day.
Frequent training is not necesary for strength. It is just 1 method. There are many ways to gain strength, but they all need to be consistant and progressive.