silverdieselcorolla, after rating the intensity decreases over time due to there being less to learn. Not that you ever stop learning but over time you're simply less likely to encounter something novel - you have a broader and deeper pool of knowledge and experience to draw from. You use the skills you've learnt day in and day out so they become second nature.
Unless you're working a tower that closes overnight (e.g. a GAAP or secondary tower such as MB or EN) you'll eventually work a roster that incorporates shifts that cover the full 24 hours. Initially you probably won't hold enough ratings but after a few years you will.
Rostering is fairly inflexible with limited scope for swapping shifts, particularly out of the cycle you're working. You might be able to swap a morning for an afternoon shift on the same day but swapping a shift on one day for one on another can be difficult. Can make regular external activities difficult. I hope you like working Christmas Day....
That said you're generally not doing battle with everyone else driving to work, don't need to go to the bank during your lunch hour and can take the kids to school or pick them up quite often. Of course you'll be working more weekends than not and will be trying to sleep when the neighbours are mowing the lawn so it's not all good.