When we both work we have wages paid into seperate accounts and then an equal set amount paid into a joint account for household stuff and joint purchases.
When other half went back to Uni for a year postgrad she had no income, followed by a prolonged period of unemployment as she tried to get a new job in a higher position with her new qualification (covid19 made getting into her profession at the time very difficult) and she was on JSA. For those two years we decided I would just have my total wage paid into our joint account and she had free rein at it. We always discussed big purchases before anyway and neither of us are high rollers or brand queens so we didn't really have any issues. The idea of setting a 'spending allowance' never occured to me since I trust her to be sensible and would never begrudge her anything. The idea of an 'allowance' infantilises a partner and creates a power inbalance. In an equal relationship that is weird at best. If spending or finances had become an issue I am sure we could have sat down with bank statements, a spreadsheet and compromised on a spending plan for both of us which we could agree on. Being a SAHM is a massive responsibility and job. Stiudies show that between child care, home maintainence/cleaning, laundry, shopping, cooking, school runs and home administration a SAHM's work is worth the equivalent of £185,000 a year. Any partner who would begrudge you free and equal access to their wage considering the value you are adding to your shared lives and family is someone you should get rid of.
I have had experience of friends in my friends group who became SAHM or who took career breaks and became dependent on 'allowances' given by husbands, or whose spending was monitored. I have been out with friends and seen them refuse to make purchases because of what their DH would say...it felt weird. These are well off people and yet these previously strong and independent women were scared to buy a coffee, or have a cocktail with dinner because DH would question it.
Joint account all the way.
n.b.
I do understand that extenuating circumstances such a gambling habits, alcoholism, certain mental health issues, impulsive spenders, shopping addicts etc etc. Partners may have to consider something more rigid like a 'spending allowance' but ordinarily I disagree with it.