Daily specials have inbuilt 10% discount already and vouchers are a further discount. If u get 30% voucher, its roughly equiv to a 40% sage treasure discount and lets be honest, when was the last time u saw 40% in sage on something that was actually useful. So a 20% discount voucher is alrdy pretty decent imo. Having said that though, this weeks rng looks pretty bad for vouchers, just like the prev one using mission mobilisation box...
They should stop with the rng vouchers and give guaranteed ways to get them (like the prev spend 3k ingots and get 30% voucher). They can keep 50% at rng if they must, cos honestly 50% really is way too good.