In a 7-men rotation, backups are only playing around 8' per position (around 9' if the starters' staminas are lower), which means 40' on average for each starter. It's still not worth having really good subs if the 3-position sub will only play 22-24' and the 2-position sub 16-18' on average.
I'd argue that it might be. If the sub and the starter have similar quality, that means that the sub would perform better than the starters (due to stamina skill decay) in those 22-24/16-18 mins he is on the court. There's always the risk of injury/foul-out that those subs cover as well.
Of course, it will be even better if further adjustments are made, so that the subs could spend a little more time in play, say 28-32 for three positions and 20-24 for two positions. That would bring the starters' minutes to ~37-38 which would be ideal.
I still believe the best way to counter short rosters is via GS, of course.
BBB: 2 (S37 S38); Top tier: 7 (S35 S36 S37 S38 S39 S41 S63); Cup: 9 (S25 S35 S36 S37 S38 S39 S40 S41 S61)