One of the critical elements of serious dance history is cross-checking what the dancing masters says in dance manuals against the evidence we have -- if any -- of what people actually did. Those two things aren't always the same. Dancing masters generally explain what people ought to be doing, sometimes interspersed with lengthy complaints about what people are doing instead. Both rules and complaints are useful guides, depending on whether one wants to strive to dance well and politely by period standards, or dance badly and rudely, as no doubt happened plenty in practice.
But the very best evidence comes from the letters and diaries of people who actually lived in the relevant era. Here's a great example of how a letter supports something that dancing masters wrote about in the Regency era: people of the same gender dancing together.