Good luck fighting it but four on four off shifts are brilliant.
I found them quite brutal and incompatible with any kind of work:life balance.
For starters, it makes it impossible to do any kind of routine social or leisure activities. Weekly yoga class? Nope. Weekly pub quiz with your mates? Weekly ramble followed by Sunday roast in a country pub? Nope. Weekly evening class to learn French or Chinese or BSL or flower arranging or pottery or motor mechanics or upholstery or whatever? Nope, nope, nope, nope, etc.
Also, because of the condensed hours, I found that I'd be knackered on the first day off, catching up on sleep, then catching up on chores, doing cleaning, laundry, shopping, etc. And then the fourth day off, you can't make the most of it, because you're conscious of having a long day the next day, might have a super early start the next day, so you're reluctant to risk socialising with mates in case you're having too much fun and stay out too late.
So while ostensibly it sounds great to have four days off, your first day off is written off due to recovering from working a week's worth of hours in only four days, then you have a two day weekend, then admittedly you have an extra day but you can't maximise it, because you've got that Sunday night feeling.
So your whole life (and physical and mental health) gets fucked over due to working irregular hours, antisocial hours, long days, and you don't really get four days off by the time you factor in writing the first of four days off for recovery time and chores and then being restricted in terms of your activities on your last day off because you're conscious of going back to the grind and not wanting to overdo it at the start of your working 'week'.
It's shit.
I don't know why they don't do 3-4, 4-3, 3-4, 4-3, where you work at least three of the same long days, and every other week you'd work the shared middle day with your opposite number colleague. At least that way you'd have a chance to engage in regular leisure and social activities.