I stored up my allowance for two months simply to purchase satisfactory UC to get the Lucky Spin Royale flow
https://www.scribd.com/document/1074360768/My-First-PUBG-Mobile-UC-Top-Up-Story-Instant-Delivery-and-Discounts-199113
I kept up my allowance for 2 months simply to buy adequate UC to get the Lucky Spin Royale pass, making the grind particularly worthy it.