The Weekly Distribution sets what percentage of the week's budget goes to each day, and the total must add up to 100% (the counter turns green when it does). The ready-made presets are: Uniform (same weight every day), Gradual (grows through the week, peaking at 25% on Friday and Saturday), Weekend (concentrates 30% on Saturday and 25% on Friday), and Weekdays (18% from Monday to Friday and 5% on the weekend). You can also type the percentages manually for each day. In Entire Account mode, the distribution only applies if you customize it. Otherwise, the system analyzes the last 30 days of performance and distributes the budget automatically by day of the week and by campaign. Bid Cap optimizations don't use weekly distribution.