If you're getting bad luck with card draws and just can't get that spire/ewer, it's a greater dps loss to just hold onto that Balance/Arrow instead of using it. Personally, I wouldn't say to hold it for more than 2 draws tops, or that's potential dps you're just missing out on.

Incidentally, did they do something to the RNG? Last three days all I've Drawn are Balances and Arrows, and the rare Spear, literally nothing else. What gives?