It's similar to the systems administrator dilemma.
Do your job well, it looks you are not doing very much, why are we paying you?
Everything is on fire, it looks you are not doing your job properly, why are we paying you?
I've worked with a few engineers over my career like the person you described and frankly they are worth their weight in gold, been able to bank on their output working reliably and consistently over time is hugely valuable, doubly so when what they do is the bedrock of many other things.
Of course the unhurried, thoughtful person looks like they are slacking and the hurried, frantically working person looks like they are a hard worker.
Fundamentally it's because impact is harder to measure than perception.
Do your job well, it looks you are not doing very much, why are we paying you?
Everything is on fire, it looks you are not doing your job properly, why are we paying you?
I've worked with a few engineers over my career like the person you described and frankly they are worth their weight in gold, been able to bank on their output working reliably and consistently over time is hugely valuable, doubly so when what they do is the bedrock of many other things.
Of course the unhurried, thoughtful person looks like they are slacking and the hurried, frantically working person looks like they are a hard worker.
Fundamentally it's because impact is harder to measure than perception.