It depends on the tickets I'm assigned, and that can be feast or famine. I don't possess any decision making power in the tasks I am assigned, and to be honest I'd rather not have it.
Sometimes the tasks I'm assigned are merely to reconnoiter the feasibility of taking action, and not to actually develop or commit code changes.
In other cases I'll be asked to change something that required 30 seconds of effort. Maybe flipping the value of a configuration flag from true to false, et c.
On average, I'll deal with tickets that involve several hours of stepping through nested loops in a debugger and inspecting log output, or wading through long-running SQL queries, and then committing changes that improve upon an existing body of work.
More rare are the intermediate tickets, that might take days and weeks of effort, and roll up into a larger project spanning many weeks or months across multiple developers. Tickets that keep me continuously tasked for multiple days at a time experience differing degrees of productivity, depending on hundreds of variables, and some of those variables are the work environment.
If something's really important and difficult, and the colleagues I'm delivering it to possess an understanding that it requires my undivided attention, then I'm provided with exactly that. I'll ask for a quiet office to camp out in, with a door I can lock, if I need it.
No matter what, I'm in the office, regardless of whether I'm idle, during a dead zone of activity while we wait for other people to provide requests or complete planning through interminable daily hours-long meetings, or whether I'm swamped in a firestorm of emergencies that divide my attention across several immediate worries.
At the end of the day, I'm paid for my time, and sometimes that pay is what will retain me through period of waiting for my turn at the trigger. If you don't pay me for that time, then I'm a temp, and not a regular, full-time employee. That's how it works.
I'm not a founder, or a partner, so I don't receive bonuses or a share of profits based on the success of calculated risks. In exchange for that, I accept the status of a regular persistent relationship. Eight hours a day, 50% of my waking time on this plain of existence, on call as a resident expert.
I stopped worrying about a perfect, even flow of continuous, normalized engagement a long time ago. Almost every field out there has varying degrees of hurry-up-and-wait temperament, and that comes with the nature of human interaction.
It's not productive to mince parsimonious hours and minutes, in my opinion, when it doesn't reflect the realities of human interaction.