Single app has worked better for me. I am at 4 months of journaling and planning every day (I have used notion for a few years). When I was using desecrate apps I would go 1-3 weeks before system would fall apart.
For me the main pros are: Ability to move and copy elements from tickler to daily plan so easily. Ability to link todo's to documentation. Ability to take notes in a way that works with how I think, and ability to take handle incoming thoughts as fast as they need to be documented.
Main cons are: only "date time" construct in databases, I would prefer a "time" construct. Offline. Data portability.
> I feel like maybe this is the heart of it, having a personal cache to make a temporary mess in until you have time to clean it up later. I could see that being useful - though id want to move everything out of that place and not organize things within it
Cal Newport has a `working_memory.txt` file on every one of his desktops that he chucks random information into and then processes it at the end of the day. Maybe a system like that could be more your jam.
I might one day work up the courage to use [https://bangle.io/](https://bangle.io/) + github. Feels like owning my data + a bit more flexibility could be nice, but that seems like a lot of work.