Nothing is useful until you define where do you want to go. I am privileged to enjoy the world the way it is with all we've got thanks to these concepts, despite them obviously being the primary sources of stress (I bloody wish people didn't use clocks for anything but science). But billions of people and animals struggle and could possibly live happier lives if we didn't get "here". I think the optimum is in the middle - use time and identity but keep aware these are just concepts and avoid taking them seriously. Never really self-identify with your "identity". You are you, not your profession, public image, body appearance, gender, age, ethnicity or anything. Believing "identity" is something real, let alone important, leads to all sorts of struggle and existential crisis ultimately. Just look at some unhappy old people struggling to make sense of their lives after they retired and their children moved away. I feel like I would already go nuts or something if I seriously perceived time and identity the conventional way, wouldn't even need to get old. This probably is what turns people into alcoholics or worse.