Yep, there was article that recently came up on Hacker News about maintaining some slack in your work schedule so that you can always be responsive when an issue comes up. I'm having trouble finding it because searching for "Slack" on Hacker News turns up a whole other range of things...
I feel like I am in a similar boat to OP. Often feeling like my regular work doesn't take up a full week and not trying to fill up every bit of that 40 hours. I also spend a lot of my time "poking around" and not doing my own work. Seeing what others are working on, learning random things that may or may not be applicable to my job. But performance reviews come around with words like "very responsive!" and "always knows what's going on in the program and can jump in to any project"
I feel like I am in a similar boat to OP. Often feeling like my regular work doesn't take up a full week and not trying to fill up every bit of that 40 hours. I also spend a lot of my time "poking around" and not doing my own work. Seeing what others are working on, learning random things that may or may not be applicable to my job. But performance reviews come around with words like "very responsive!" and "always knows what's going on in the program and can jump in to any project"