Great for them, terrible for everyone who had to work with them. When one person has significantly less availability than everyone else, the rest of the team is forced to structure their activity around catering to that person's schedule.
Superstar engineer only works a couple hours per day? Prepare to block that time off in your calendar so you can try to catch them to coordinate that work you need to do together. Rockstar coder unavailable every Friday? Better hope they're not blocking your work, otherwise you're waiting until Monday to make progress. Or more realistically, you're going to waste all Friday trying to solve something on your own that could be finished 10x faster if you could get 15 minutes of that person's time.
> Don’t lie, don’t make up excuses, but be prepared to say I did xyz as planned.
The fallacy is that for most tech jobs, that "xyz" is rarely the end of the story. Planning isn't perfect and we almost never know the complete scope of a task or project at the planning phase.
The end result is a lot of work shifted to other team members who are forced to pick up the slack simply because they're available and reliable, unlike the person who disappears every Friday or spends every afternoon at the gym.
This may work in a hypothetical workplace with perfect planning and perfectly isolated work units, but in practice it just moves the excess work burden to other teammates. You're not sticking it to the company, you're sticking it to your team.
When I transitioned to management I made a point to try to balance workload and availability across teams. It often makes more sense to let go of superstar engineers who are only available 4 out of 5 days per week and only working a few hours per day, even if their work is good in isolation.
A healthy team requires everyone to play by similar rules.