How important is hardening off?

I seem to have a conflict. I've never hardened off my seedlings before and have had no problems either. But this year I'll be doing multiple things for the first time. I'm planting lots more varieties, doing succession planting, and using an oscillating fan to strengthen the seedlings. Also giving them more light.

The conflict is with the succession plantings. The time to harden off the first seedlings seems to be much earlier than the later ones; but they're all going to be in the same trays. Two questions.

Will moving the whole tray out hurt the later seedlings?

Will using the fan mean I don't really need to harden them off anyway?

Thanks, Jack Smith