Alternative suggestion too long for a comment. I wrote code to use WinAPI timers:  https://codereview.stackexchange.com/q/229656/146810

These can be used to call a method which may be:
 - Stopped with the stop button
 - Disabled when Excel closes
 - Even stopped with the End statement
 - Can handle Errors and launch debugger (just make sure to continue execution after)

### Standard Module

```
Option Explicit

Sub StartContinuousRecalculating()
    Dim cellToRecalc As Range
    Set cellToRecalc = Sheet1.Range("A1")
    'spawn a new timer instance, it will call "RecalculateCellProc" supplying the Data argument as the userData param
    ' i.e. it will forward the cell reference to the proc every time it is called
    TickerAPI.StartManagedTimer New RecalculateCellProc, delaymillis:=1000, Data:=cellToRecalc
End Sub
```

### Class `RecalculateCellProc`

```
Option Explicit

Implements Timing.ITimerProc

Private Sub ITimerProc_Exec(ByVal timerID As LongPtr, ByVal userData As Variant, ByVal tickCount As Long)
    'Doesn't matter if we raise errors here as this is a managed timer proc, error details are logged
    'Can even set breakpoints as long as we don't click `End` during a callback, that will crash Excel
    userData.Calculate 'assume it's the range we're expecting
End Sub
```

Obviously this isn't commentary on your approach. You just may want to do it this way since it is a bit less hacky (e.g. allows breakpoints/errors, doesn't use state machine logic that's hard to follow), and you can have finer grained control over what you call and millisecond delays.

---

*CristianBuse created [another great approach][1] to these timers using 1 workbook that spawns another delegate workbook to handle the WinAPI calls with an extra degree of safety. His approach is even more stable/harder to crash - you have to set a breakpoint in the second workbook I think. But it's a bit more overhead (which may or may not be an issue for you) and Excel specific IIUC and it sounds like you want host-agnostic code.*


  [1]: https://codereview.stackexchange.com/q/274652/146810