A 90 percent time worker is a lazy worker...
All the other people in the office see that employee as "lazy Bob". The guy who isn't around every 2nd Friday. They guy who works slower than everyone else. They guy who always seems to be randomly missing from important meetings, and then doesn't know what's going on.
A 90% time employee is worth far less than 90% to the company.
Source:. Worked at a company where employees could either take a few days off after a bout of overtime, or get paid extra. Those who took days off were seen as lazy, not committed, and wouldn't get promotions or roles of responsibility.
I for one have been working 80% for two years (Germany) and have never felt more productive and motivated. And not only that, but I've also been able to use my Fridays off to acquire skills I would otherwise not have had the time or motivation to learn.
None of my colleagues ever complained about me seeming lazy or slow, quite the opposite, really.
Anecdotal evidence is, by definition, facts that are gathered in an unstructured manner which limits their probative value when it comes to supporting broader generalizations.
So, it's quite appropriate to frame anecdotal evidence as facts, though one is on weaker ground drawing generalized, conclusions from such evidence, which was the actual problem with the grandparent post.
And depending on the country it's outright illegal.
In Switzerland, for example, which has one of the more liberal (as in employer friendly) employment laws in Europe an employer can not compensate vacation days with money, except in very exceptional circumstances (i.e end of employment and employee has remaining vacation days).
Obviously working more means you get more done (assuming you don't burn yourself out), so the cost of working less to your career is nonzero, but this is practically tautological, and the stronger claim made here that it affects your reputation beyond its actual impact on productivity is not as universal in the US as people like to complain.
I much prefer working in America, or at least with Americans - but in terms of lifestyle, Europeans have it much, much better.
I had a 90% job with a large software vendor. The deal being 20 days additional vacation for 10% less pay.
I can guarantee you that during the time I worked I was a far better and efficient employee. That's based on the simple fact that I ws much better rested, far less stressed and much more creative due to the additional time off, in which I travelled the world.
Based on my anecdotal evidence I stipulate that you're dead wrong.
But most hours reductions are of the predictable continuously reduced schedule type, which is great for occupations where a defined number of positions has to be filled at all times (pretty much everything that is more reactive than active). But in "projecty" work, that predictability is of little value, the reduced-hours teammember will count fully (or more) to team size in terms of organisational overhead and task dependency delays, but will contribute fractionally less. It's not the lower amount of total hours in that scenario, but the permanent asymmetry.
I've worked with some of the best people in the world building billion dollar systems in small teams. People have different work habits and some of the best people I've worked with worked on their own schedule and always produced world class results.
What you're describing seems to be a mediocre environment where the perception matters more than the results. And not only that, but you seem to present your perception as universal within your company.