Anytime someone on the internet goes "at my company, we grind" -- you get the angry internet mob at their doorstep telling them how wrong they are. It's interesting how "taboo" the expectation of working hard as become (in the tech scene?). I wonder if many of these instances are hyperboles getting taken too literally or if too many people have been burned from bad management. To be clear, I have no problems personally with working stable hours each day -- it's this strange internet group-think of any exception to this to be considered hearsay.
Especially in a smaller company, like many startups, there is not a lot of foundational leverage to work with. It's ground zero -- you're starting from scratch. And the chances are, if your workstream looks extremely stable -- that's probably thanks to a colleague that gave a shit and went the extra mile to make it easy for you. And if this was possible with minimal effort, great! You've probably just hit a career jackpot with well seasoned co-workers. Cherish that, but also realize that you may be an outlier. Just think, how much time have others put in work to support that stable workstream you enjoy day-to-day? How many years of collective experience did it take to curate an effective workflow and how did it fit so well with your existing team? (I suppose the exception here could be that the company as a whole moves at such a slow pace, there is no required sense of urgency whatsoever -- and this is fine! Different companies require different factors for success, as long as they can make money.)
Otherwise, you're tackling a differently shaped problem -- likely on a weekly basis. And it takes time, and some skill to break down these problems into more predictable chunks of work. But nothing is perfect -- far from it really, just look at how many tech people shit on JIRA and agile in general. Do people really hate JIRA or are they just upset at how bad we as humans are at breaking down problems?
A lot of online chatter I read conflates working hard and burning out. It's definitely a management problem to set the correct set of expectations for teams to succeed. Different states of a company requires a different set of variables to optimize for. And while fear of underperforming is a very demoralizing workplace, a workspace where your effective work hours are nonexistent is also problematic as an industry. As with many things in life, a good balance between these two extremes is probably where a "right" answer lives for most companies.
Regarding burn out, I think is a separate issue entirely. There could be a number of difference factors at play here:
In the end, burn out is unique to each employee -- with their own factors and motivators. It doesn't sit right with me that "working hard" has turned into this scapegoat. They say you can work "smart", but what does that even mean?
Working well from my experience ultimately comes down to time management. How are you allocating your time? What does your day look like? Can you identify previously solved problems? How can you tackle this better next time? What is the "right" amount of time to allocate to certain things? It's difficult for me to imagine someone saying they work "smart" without having worked "hard" before. "Smart" indicates you've been able to establish a better pattern for solving whatever immediate problem is at hand. You're going to have a hard time modeling solutions for problems you've never even remotely seen before. Working "smart" in my eyes is being disciplined about expanding your mental models so that you can more effectively map new problems against past experiences. And for someone to find continuous success here, they need to have learned of this in some way, either through experience or external resources -- both of which take a non-trivial amount of dedicated time.