Allow to keep previously placed temper (like enchanting)
Same temper can’t roll twice in a row or allow for a affix % only roll so once you get the temper you want, you’re just fishing for a better %, make it cost 2 rolls just for good measure.
Problem solved unless you get greedy and try to push for a maximum affix on the temper you want as you are now burning 2 rolls for a few % higher.
At that point “bricking” (such a stupid terminology) is because -you- got greedy knowing full well that you could potentially ruin the item for a slight increase in affix % to what you already got.