I much prefer the first.
School shouldn't be impossible, but you shouldn't have a charade of schooling.
Obviously, extra practice is a good idea.
Assignments students do in class isn't "homework". It's just classwork. All my math classes had both.
Perhaps you mean study halls? Those were uncommon until highschool where I grew up. And most of the time people spent there was not studying.
And I mean setting aside some time during the class itself, not a separate "study hall" period. Obviously class time is precious, so I don't expect there to always be enough in-class time to finish assignments. But even having a little in-class time for students to get started - and when the teacher is available for help those in need - would go a long way towards encouraging students to do the work themselves and not cheat.
And of course part of my strategy is to make "homework" shorter (5-15 min). That should also reduce the temptation to cheat and increase the likelihood students can even complete them in class.