Unless you are performing work with genuinely tight deadlines (e.g. surgery), what stops you from taking breaks at least every 45 minutes? Not who tries to stop you from taking breaks. What actually stops you, if anything?
A fifteen minute break that saves you twenty minutes of work is a net win. Sometimes a fifteen minute break saves you hours, days, or years. People who use high-pressure sales tactics (and artificial deadlines at work are a high-pressure sales tactic) know this. They want to steal those hours, days, or years away from you. Will you let them?
How do you plan for your breaks? You will have breaks, after all, whether you want them or not. It’s a question of whether you’ll have a restful break or whether you’ll have to watch something - or someone - shatter and break in front of you.