Frankly there aren't that long queue times for DSP anymore. Unlike at the start with 2h+... usually 30 min is max 90% of the time. Often less. But if you want to rush level then yeah fates. Frankly I'd suggest queue for DF then do fates while waiting. But not that you will be doing a LOT of fate grinding when you go for atma weapon - so there is real danger of burnout depending on luck.