The way I see it working would be that the daily budget would fluctuate depending on the days when you underspend or overspend. If it says £30 per day but you spend £100 then the rest of the month would decrease slightly to £26.70 or something. And then days when you spend less than the budget would then increase it. You’d never get told you’re spending too much because it’d only be affecting the following days spends which is the same as what you would do for a monthly budget