The engineer doesn't decide the schedule though. Usually their activity is controlled by having to do X tasks in time(X)-time(Y)=available_time, with Y being any set of reasons, political, financial, organisational that the engineers will accept as true.
Then as engineer what can you do? Either assume toxic Management (and switch Jobs) or do a subset of what you would usually do, and that means optimize for your own browser first and only work on bugs known to your management for the other browsers.
Admittedly, when I was at Google, I only worked on three different products. However, while there I had no real deadlines. My work was done when it was done. Performance was measured in quality and impact. This was in fact a part of the culture that was communicated to my team on multiple occasions.
With that said, there is some indication from the outside that the culture is changing. It can be difficult to sustain culture over time, especially in the face of massive success.
its not always possible to sustain that philosophy of work economically for all businesses. I'm not defending every case of it, just that there are legitimate reasons why speed is valued over quality in certain cases.
Then as engineer what can you do? Either assume toxic Management (and switch Jobs) or do a subset of what you would usually do, and that means optimize for your own browser first and only work on bugs known to your management for the other browsers.