I always ask for questions during my Craftsbury strength training workshops, and one of the most common revolves around how many sessions per week rowers “should” be strength training.
The simple answer is most likely two times per week, and maybe three.
Two ~60-minute full-body strength training sessions per week is enough for most rowers to make progress in strength, power, and muscle mass to support rowing performance. Younger rowers with more time, energy, and recovery may do 60-75 minutes of higher volume training, while masters rowers may do 45-60 minutes of lower volume training. So, 2x/wk for 60 minutes +/- 15, which includes a ~15-minute full-body warm-up phase.
I will do three sessions per week with rowers who want to prioritize strength training to make greater gains in strength, power, or muscle mass during the off-season and early pre-season training phases. We typically use an upper/lower/full-body split, with the deadlift on the “full” day.
Some rowers who want to focus more on rowing during the in-season, or who have a particularly rigorous race prep phase, will do a weekly plan of one longer session with weights and one shorter session with bodyweight only. I call this the “one-and-one” plan, and I use it most often in HOCR prep.
The more complex answer is a question: what is “should”?
“Should” depends on your personal goals. I have coached rowers on my “minimum rowing strength training plan” with 2x/wk of 30-45 minutes, for rowers who are short on energy, equipment, or desire for strength training, but still want to get it done. I have coached rowers who love strength training and can’t wait to finish racing season to get to 3x/wk strength training in the off-season. Most rowers are somewhere in-between, and the majority of rowers I coach give it a solid ~60 minutes 2x/wk and move on to the other important training and the rest of their life outside of training.
More than 3x/wk strength training or sessions longer than 75 minutes tends to result in impaired “other training,” ie. rowing, erging, and other aerobic training. For rowers who care less about their rowing performance, a little bit of impairment in exchange for the kind of training they enjoy more is a fine trade. Rowers who still want to focus on rowing performance as the priority goal typically run out of energy, time to train, and/or recovery to improve from the training for more than 3x/wk strength training.