It just depends on if you can pay the bills and that 20 percent is just for extras.
To compare, my wife decided not to work but to stay home with the kids. That is an extra salary that we don't have. But we don't really miss it. We have less extras but more time off. She can do the housework while I am at work, so that we don't have to both do it after work. And and we don't have to pay for daycare or mess with picking up/dropping off the kids etc.
Sometimes a simpler life is more important than money. So if you could still do fine with 20 percent less money, then I would say go for it. Life is to be lived not survived.
On the other hand if you need every penny to pay the bills, then you just can't cut back.