No way was Chrono Cross 20hrs. That game took me over 40 hours, and I missed out on some major stuff. Also, howlongtobeat.com has the average completion time at about 44 hours.
Imo 20hrs is just too short for an RPG, unless it's a cheap indie. If I buy an RPG I expect to get at least 35hrs on the main story + a few sidequests. If I wanted a 20hr or less experience, I'd buy a linear, story driven action game, like Uncharted, or Bioshock. Those provide more "enjoyment per hour" than your average RPG, considering they have no inventory/party/resource management, or traveling. It's just one setpiece to the next. Better graphics too.
I doubt anyone would beat CC on 20hrs without a guide or a lot of training, it's definitely not a 20hrs long game, indeed.
You cant train in Chrono Cross... there is no experience. So grinding, a major time sinker in every JRPG is eliminated. Chrono Cross has no major sidequest, there side activities, but nothing like typical Jrpg time sinks. Chrono Cross is incredibly linear - Impossible to get lost, you will always nowhere to go. I spent entire summer playing Chrono Cross multiple times along with Digimon World 2. Chrono Cross definitely can be beaten 20 hours.
On a second note - He did that math shit above to spoil anything for future buyers. Then like a twat, you go right behind a do it anyways... *eyeroll* put on that topic -
SO1 = 1p
SO2 = 1 1/2p
SO3 = Elicoor is the only legit plant. Every other location is just area of another plant.
SO4 = is the latter of SO3, only visit specific areas of other planets
Star Ocean is not about visiting multiple planets, but the effects of young planets/civilizations getting caught up in Universal disasters that most of time evolve Earth Federation and their enemies.