## Is your feature request related to a problem?

#4947 added a new query to the backend – time to convert. It works well, just one point is kind of rough: bin width and count.

## Describe the solution you'd like

Currently the number of bins is hardcoded. Ideally we should have two options:
- return a user-specified number of bins,
- otherwise infer a reasonable number of bins using some algorithm (auto option).

@alexkim205 [suggested](https://github.com/PostHog/posthog/issues/4855#issuecomment-872423877) the [Freedman-Diaconis rule](https://en.wikipedia.org/wiki/Freedman%E2%80%93Diaconis_rule) for determining bin width (and interval based on that), but unfortunately from my testing its formula would not be the most practical – it's great for keeping a pretty constant "smoothness" of the histogram esp. with normal distribution, but we face some additional constraints that make it less than ideal:
- we can't have histograms too dense visually in the UI, from my testing a practical limit is 60 bins (above that it gets too dense),
- our data generally doesn't follow much of a normal distribution.

Clamping may help though, or maybe a different formula may work better outright – I'll be testing this.

## Additional context

Issue pertaining to the experience of time to convert: #4855

#### *Thank you* for your feature request – we love each and every one!

posthog/constants.py
INSIGHT_FUNNELS = "FUNNELS"
INSIGHT_PATHS = "PATHS"
INSIGHT_SESSIONS = "SESSIONS"
INSIGHT_RETENTION = "RETENTION"
INSIGHT_TO_DISPLAY = {
    INSIGHT_TRENDS: TRENDS_LINEAR,
    INSIGHT_STICKINESS: TRENDS_LINEAR,
    INSIGHT_LIFECYCLE: TRENDS_LINEAR,
    INSIGHT_FUNNELS: TRENDS_FUNNEL,
    INSIGHT_PATHS: TRENDS_PATHS,
    INSIGHT_SESSIONS: TRENDS_LINEAR,
    INSIGHT_RETENTION: TRENDS_RETENTION,
}
TRENDS_STICKINESS = "Stickiness"
TRENDS_LIFECYCLE = "Lifecycle"
SESSION_AVG = "avg"
SESSION_DIST = "dist"
SCREEN_EVENT = "$screen"
AUTOCAPTURE_EVENT = "$autocapture"
PAGEVIEW_EVENT = "$pageview"
CUSTOM_EVENT = "custom_event"
DATE_FROM = "date_from"
DATE_TO = "date_to"
ENTITIES = "entities"
ACTIONS = "actions"
EVENTS = "events"
PROPERTIES = "properties"
SELECTOR = "selector"
INTERVAL = "interval"
DISPLAY = "display"