## 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
STRICT = "strict"
    UNORDERED = "unordered"
    ORDERED = "ordered"
class FunnelVizType(str, Enum):
    TRENDS = "trends"
    TIME_TO_CONVERT = "time_to_convert"
    STEPS = "steps"
RETENTION_RECURRING = "retention_recurring"
RETENTION_FIRST_TIME = "retention_first_time"
DISTINCT_ID_FILTER = "distinct_id"
class RDBMS(str, Enum):
    POSTGRES = "postgres"
    CLICKHOUSE = "clickhouse"
WEEKLY_ACTIVE = "weekly_active"
MONTHLY_ACTIVE = "monthly_active"
ENVIRONMENT_TEST = "test"
ENVIRONMENT_PRODUCTION = "production"