Some people swear by it. I had a Yammie 2 stroke that I ran Seafoam in the entire time I had it and it had no effect at all. Even after having the carbs cleaned, it never ran right. On the other hand, I have a buddy who claims it brought back a couple of motors from near death. As long as the motor starts, runs good and idles with no lean sneeze, I would just keep fresh gas in it and go. I would use whatever the manufacturers suggests to keep carbon buildup minimal and go with it. JMHO.
2015 Seaark 1872 MV CC Etec-90
Two Helix 12 CHIRP SI's, , MinnKota Riptide ST80/i-pilot Link, Bob's Hydraulic
2018 Robalo R180 CC, Yamaha 115
Bitter Gun Owner