Help with SQLite reliability (idle time & timeout errors)

Is there any more information about this ‘idle time’? I’ve also been struggling to interpret this number. I only have a small scale deployment so not encountered any issues with sqlite but would be nice to understand these metrics a little better. What are (problematic) small values?

Is there any downsize on drastically increasing the pool_size? Currently I use 5 (which I think is the default), any downsides to going to 50? Soon I expect some small bursts of activity for my app, so would be nice to fine-tune in advance so I don’t need to worry about it!