I think the point is that OP is short-changing his/her own career. If you're doing the equivalent of 1 day of work over 5 days, and it's OK to your manager, you are performing at what most FAANG companies would call "Meets Expectations" which is just treading water career-wise. If your goal is to just tread water for the rest of your life and take a paycheck, then by all means keep doing it. If your career goals include climbing the ladder, working on something "meaningful", joining a high performing team with cool technology, standing out and getting prestige, whatever they are, you're probably not going to get there by relaxing on the "Meets Expectations" cruise control setting.

One thing I wish I learned earlier in life is that your career is your responsibility, not your manager's, not your company's. I spent way to many of my early years asking "What tickets should I work on now, boss?" and too few asking myself "Where do I want to take my career long term, and what steps do I take now, next year, and next 5 years, to get there?"