I will if I like it, just like I did in GT5
They took the risk, that schedule is very exigent, and now they're facing the consequences, It wouldn't have failed if instead of "every month", they said "Every two or three months", less presure and more opportinuties to mess up
This is to keep players from having easy credits method
I think the same as you, supporting multiple games at once, not a good idea, look what happened to Call of Duty and what is happening to Battlefield, they have multiple games supporting and both franchises are facing serious problems, PD, on their part, have little experience supporting multiple games at once, they released GT5 late in the PS3/360 generation, and other studios have learned how to support multiple games at once.
When PD released GT4, there was no such way to support the game, let alone GT3.
Now, GT5P and GT5.. GT5 evolved very slowly when GT5P was still supported, once they stopped caring for GT5P, GT5 started to evolve in a faster way, and there's no way to deny that.