SHIELD's biggest issue (well, one of the many) is that it couldn't be its own show and had to react and set-up the Marvel Cinematic Universe. (Personally, I think they should have just waited to premiere it AFTER Cap 2 and get to the good stuff of Coulson trying to save a fractured SHIELD.)

Now DC is forcing both Arrow and Flash to serve as set-ups for Legends of Tomorrow is wearing thin for me. Especially Arrow where they've done my pet peeve of introducing a villain and then having him inexplicably hang out and do nothing for a few weeks. Damien Dahrk is just chilling the last couple of weeks. Harrison Wells was apparently just roaming the halls for the first half of Flash.

Spending time bringing back Sarah and Ray and re-establishing Firestorm all so they can go off to another show is holding back the main shows IMO.