Perhaps you could incorprorate a bit of both strategies by buying some 3* fasttrainers as sub. I reckon they're not (much) more expensive then a "normal" 5* player. They will get your avg Q down a bit, but it's not like you're wasting T or cash as you'll be able to sell em without losses if you keep and train them for a little while. On average they will perform quite adequately if you use them, while some might turn out to be little gems.