Sort of, but not in one play session. Episode 1 consisted of 9 challenge missions, they are usually referred to as "1c1" meaning Episode 1 challenge mission 1, up to 1c9 and then Episode 2 has its own like 2c1. So essentially, you play each of these 9 missions from Episode 1, in single sessions, and your total accumulated time for all of the challenge missions combined has to be less the 7 hours total in order to qualify as "S Rank" and be able to obtain an "S Rank" Weapon. This is the only way to obtain S Rank Weapons. The first mission, 1c1 is relatively short, under a half hour if done correctly, but then some of the missions are an hour or so. The cool thing is that even if we do all 9 missions from Episode 1, and our total time comes in at 7 hours and 15 minutes or whatever the time is, we can simply go back to missions we know we took a long time on and drop those missions down. Once our total time is under 7 hours we qualify for the S Rank.
So its actually pretty forgiving, it just takes time to learn the maps, and what paths are required to progress, and what paths lead to better drops. Your character is scaled for that particular challenge mission, and given specific equipment loads. So for example, 1c1 is all level 1 characters with the basic starting class items, however 1c2 will start us out at say level 6 and hunters may start with a Sword, while Rangers start with a handgun still. Your loadout is premade, but monsters can still drop randomly throughout.
Additionally, each player has a scape doll, and if anyone dies and cannot be revived either by a player or a scape doll, the challenge mission fails for everyone and the time is not counted.
So as an example, lets say we meet up Thursday and play 1c1, but we all have no clue what areas are required or what areas are dead ends, and it takes up 30 minutes. Well, we know that 1c1 should take way less then that, so we can go back in and knock that time down to 18 minutes by learning the map. We then have 8 more missions that can take a total of 6 hours and 42 minutes to qualify for S Rank Weapons.