Question: Is there a way to set hangfire recurring jobs every few seconds?
I do not seek a solution where fire and forget task creates another fire and forget task, and if not, what are suggested alternatives?

Answer: 
Not sure when this became supported but tried this in ASP.NET Core 2.0 with Hangfire 1.7.0. The following code schedules a job every 20 seconds:

```
RecurringJob.AddOrUpdate<SomeJob>(
    x => x.DoWork(),
    "*/20 * * * * *");

```

If I am not mistaken 6 tokens (as opposed to standard 5 tokens) is supported due to Hangfire use of [NCrontab](https://github.com/atifaziz/NCrontab) which allows cron expressions with 6 tokens (second granularity instead of minute granularity).

Hangfire dashboard also nicely shows the small time interval between runs:

[![Hangfire dashboard](https://i.stack.imgur.com/RLeYF.png)](https://i.stack.imgur.com/RLeYF.png)
I think anyone who is against allowing a recurring trigger of less than 1 min is short sighted. After all, is 55 secs any less efficient than 1 min ? It seems so arbitrary! As much as I love Hangfire, I've encountered situations where I've had to steer a client to Quartz.net simply because there was a business requirement for a job to run every 55 secs or alike.

Anyone who makes the counter argument that if it was configured to run every 1sec it would have a serious impact on performance is again taking a closed view on things. Of course a trigger with a 1 sec interval is probably not a good idea, but do we dissalow 55 sec or 45 sec for the unlikely situation where someone will choose 1 sec ? 

In any case, performance is both subjective and dependent on the host platform and hardware. It really isn't up to the API to enforce opinion when it comes to performance. Just make the polling interval and trigger recurrence configurable. That way the user can determine the best result for themselves.

Although a background process which is orchestrating a job to run every 55 sec may be an option, it isn't very satisfactory. In this case, the process isn't visible via the Hangfire UI so it's hidden from the administrator. I feel this approach is circumventing one of the major benefits of Hangfire.

If Hangfire was a serious competitor to the likes of Quartz.net it would at least match their basic functionality. If Quartz can support triggers with an interval below 1 min than why can't Hangfire!