I don’t think it’s about the number of minutes saved per se, the value to me is avoiding any morning panic because something can’t be found (like clean laundry hasn’t made its way back for some reason) and more importantly, the feeling of being ready/prepared for the next day.
This is the key - it's not necessarily specifically about saving time in the morning (though it does help) it's about physically setting the items out in the evening, when you have all the time you need, in whatever way makes things more streamlined and stress-free in the morning.
This is just something I have always done without thinking about it, it's second nature to have everything ready the night before - bags are packed and ready in their Kallax cube, shoes at the door, clothes "laid out", lunch bag already packed with none perishables so that all you have to add in the morning are the things from the fridge and/or make a sandwich etc - so that you know that in the morning you can just get up and go without having to start dealing with problems when you're on a deadline to get out of the door.
If there are missing trainers or a lost hairband, if a permission slip needs to be signed, if a lunchbox didn't come home from school or the only school jumper is disgustingly filthy because it got dropped in a puddle on the way home then knowing about it in the evening, because you have set everything out so it's ready for the following day, gives you the maximum amount of time to deal with it with the minimum amount of stress.
It also helps model this behaviour to your children to help them be more organised without thinking about it. From when DD was small I have always had her uniform organised on a Sunday for the week but as she got older I involved her more in the process - so at first I'd do it all, then I'd get her to help me carry the basket to her room with the uniform and have her open each drawer so I could put the days items inside, then I'd ask her to find the specific items in the laundry basket and put them in the drawers 'can you get me five pairs of socks and put one in each drawer?'; then I'd let her do it herself with just me supervising; then I'd let her do it herself and I'd just do a quick check when she was done to make sure it was all present and correct, then eventually I left her to do it all herself ... Now she's in secondary and she manages her own uniform every day but she unconsciously follows the same system of having things preprepared without even thinking about it.
Because of that I think I can count on one hand the number of times in the last 13 years we've had to do a mad dash in the morning because we discovered something was missing/unwearable last minute because it happens so rarely.