This can be very easily done solo. You can pause while doing the tasks, allowing you to complete them at your own pace. Unpause then pause again when tasks change.
The challenge “Painful Employment” only had four tasks on the final day. Not sure if that’s the challenge or the difficulty, but either helps.
This is best done with 3 players (whether solo or with people in the same room or at least in party chat).
Before starting a game, go to Settings and change the last setting (Grading Curve) to Very Easy instead of Normal. This makes the game a lot easier with only 3 players. My family score maxed each round.
Now sign your 3 players in. Then have your VIP to change the This Week's Challenge to "Painful Employment" using the Next Episode button. The challenges for this "episode" are easy and there are 12 challenges spread out over the 3 days/rounds.
Day 1 - 4 challenge tasks
Day 2 - 4 challenge tasks
Day 3 - 4 challenge tasks
Finally tap/click the Everybody's In button and start the game.
Challenge tasks are explained briefly in the tutorial at the beginning of the game. These tasks are Gold/Yellow in color and need to all be completed to get this achievement. Some require only one player, while others require 2 or more.
Since the challenge tasks only appear every so often, the rest of your time should be spent on regular tasks to get your family score up. Selfish (red) tasks are not necessary unless you're going for the "most selfish wins game" achievement also.
Always watch your list for the gold challenges and watch for gold ones that need help. The multi-help tasks usually involve the need for communication between the helpers. One player might have to describe the requirements while the other performs them.
When playing with multiple real people, if all players communicate well and finish all challenge tasks in time, you should get a perfect grade and pop the achievement. The pause trick helps immensely.