For those 20 years I mostly worked out twice per week per bodypart but there were periods where I did a three times per week full body program. (trainingscience.net)
Popular full body programs like Starting Strength, StrongLifts 5 x 5, Jim Wendler's 5 / 3/1, and reverse pyramid training are usually done in 3 days per week so you have to spend less time in the gym to build muscle. (thescienceofgettingripped.com)