I don't see a point where time slots actually become better. On the contrary they have gotten worse compared to speed nowadays because everything i want maxed job-wise won't get sped up faster by having more timeslots. Likewise for Hobbies.
I'm at Eva and no timeslots in the world will make me increase her affection faster than speed would. Might just be better to save them for outfits.
Edit:
...not to mention Pamu. That bitch needs 60 buff to reach the next stage.
...which takes almost 10 hours
So honestly. Speed or save for outfits seems like the best options. The best jobs already cover the money needed to max out their affection with gifts :P