Replacing a larger number of words with a smaller number, does not expand to use the total time of the larger

For example replacing `a b c d e f` with `g h i` will produce :

```
[
  {
    "text": "g",
    "start": 1000,
    "duration": 501,
    "end": 1501
  },
  {
    "text": "h",
    "start": 2000,
    "duration": 502,
    "end": 2502
  },
  {
    "text": "i",
    "start": 3000,
    "duration": 503,
    "end": 3503
  }
]
```