A great question.

The first thing to understand is the idea of relative swings,
and don't forget that even they are only relative to the chart that you are watching.

I always map out 2 different scales of swing on any one chart,
a longer term swing and a shorter term swing, relative to that chart.
The longer term swing is always easier and more stable because it is based over a longer period of your chart,
the shorter term swing will tend to be more schizophrenic but easy enough to adapt with.

In short I will define a swing high and low based on how the market has been swinging the last few times,
instead of limiting myself to that swing happening correctly in a specific time frame of a few candles.

What a tricky one to answer without an image:

In this image the black pullbacks on the way down display what kind of shorter term swings are in play at that time,
the red pullbacks that follow on the way up could be easily judged to be relative to that.

This is a Daily chart and both that short term swing I have mapped out for you and the the next scale up are easy to see.
When it comes to anything faster than the Daily chart I prefer price based charts to eliminate noise and keep things just as easy.
This article displays how easy it can be to define swings on faster price based charts.
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I am most interested in relative movement based on recent history,
assigning candle high/low involves time and it won't always follow a formula like you outlined which make it a limitation.