What I mean is this: in my work (engineering), I spend most time on things that are new. Like, by their very nature, no one knows how hard it will be or how long it will take. Once you do something once, it is easier to do something similar again. Anyway, so sometimes we bite off more than we can chew and are killing ourselves to hit the deadline and sometimes we are doing a slight variant on something we did before and our tools and mindsets have developed to the point where the second version could be 10x easier than the first, even though it may be just as valuable.

Anyway, I think this ebb and flow and the constant newness of the challenges means that sometimes you have more deadtime.

If your job is to perform a well-defined set of procedures, it makes sense that you would eventually optimize so that you perform as many as possible back to back. If your job is, "here is an open-ended problem, hopefully you can hit a home run," there will be ebb and flow.

That said, I am not always happy myself with my level of effort or engagement. Whether WFH or in office I still have days where I feel like I never got traction on something I am satisfied with.