We struggle to keep track of what was actually their money and which was money that fell out of the grandparent’s pockets etc. One kid always remembered putting their money in the spot where a coin happened to be.
We do 1/3 in each of a spending account (can spend on a whim), savings account (with some rules around it), and charity money (donate to charity of their choice). We don’t need more crap so they get $1 per week per year of age (e.g. 6 year old gets $2 spending money, $2 to savings, $2 to charity account that we donate once it builds up a bit).
Some of their friends get $20 or more each week! One says they get $50, but kids say all sorts of things so who knows. One of my kids worked out you can get a pack of biscuits for $1, I can’t imagine giving my kids $50 a week and ending up with hundreds of packs of biscuits.