That’s 437 days on the international space station, in close orbit of the earth. That’s a lot different than spending years completely weightless, before having to adapt to Mars’ gravitational field.
And then there’s the impact of g-forces on the human body in flight. Fighter aircraft technology has now reached the point where planes are being developed and tested, which are so fast and manoeuvrable, any pilot would be turned to jelly; so the next generation will be pilotless. Spacecraft trying to reach Mars in less than a year would face similar issues.
The recent Cassini mission to Saturn was so successful, it beamed back so much data that all the processing power available in all the cosmology departments in all the world’s universities, are still going through it. The forthcoming JUICE mission to Jupiter is expected to provide exponentially more data (but processing power here on earth is increasing exponentially too). With all this information gathered by unmanned craft, there’s absolutely no benefit at all in sending manned craft into space; unless you buy into the fantasy that humans will someday colonise distant worlds.