At the moment the Mempool is about 10MB and people are still paying super high fees like 480sat/byte.
Every wallet, also mycelium which is very popular have to add a custom fee/size regulator, so that users can exaclty choose how much sat/byte he wants to pay.
It's very important for bitcoin users these days.
If you look at mycelium app, the cheapes fee (Low-prio) is 255sat/byte which is also very high. It whould be very helpfull if users could choose to pay 120sat/byte or even smaller.