I started working in an advertising/PR agency a year ago. It was a complete career change for me.
At my work, all our hours are billed to clients and we complete timesheets. I started on a client account which had a veryyyy tight budget. I'd get allocated a few hours of time to spend on a project, which was never enough time for the amount of work needed (think being allocated 6 hours to work on a 70 slide presentation, and go through several rounds of internal and external review). I was constantly telling the project manager it wasn't enough time, and we would get tiny amounts of additional budget like an extra hour or two of my time. Now most people would say that clients get what they pay for, and just do what's possible in the time they have allocated. But at the same time I had a manager who was a complete perfectionist, and would go way above and beyond the scope of the project and ask me to do things that would take ages. I would always have so many comments from them during reviews.
It led to a lot of stress for me, but as I was new to the company and field I thought it was normal. I thought I was exceptionally slow and inefficient because I was constantly needing to spend way longer than I was meant to on projects. I'd work in the evenings and mornings 'invisibly', thinking I needed to do so to make up for how slow I was.
I was constantly being chased for why taking in comments on 70+ slides would take me longer than just an afternoon. Constantly needing to ask for deadline extensions and more budget. Panicking over my timesheet, because an account that should have been taking up most of my billable hours each week was only giving me 15 hours work for a 6 week project.
I've moved accounts now and gained more experience, and only from working with my colleagues and seeing how long they spend on things have I been able to shake off the anxiety that account and manager gave me.