So apparently I am different and do different things. We treat windfalls differently, maybe we aren't too bright. But we managed to FIRE so maybe we aren't too dense either.
Depends on the windfall.
Prior to FIRE, when DH and I had windfalls, we would invest it, but usually in our higher risk/higher growth options. We never had anything near $100,000, so we might have split it up more, we don't have any data to back it up, but we very well could have. This special treatment of windfall strategy worked really well for us. It cut years off our FIRE timeline but never endangered our overall FIRE strategy.
I only have one example of getting a windfall post FIRE of close to that value so I know what we did with it. It was an inheritance to me specifically and in my family we keep inheritances as his or her money, so I didn't want to mingle it with our money. Since it was my money, I got to decide what to do with it. I like my usual investments, but didn't want to mingle it with those accounts so I found a different investment that I liked and plopped it in there. My goal was to put it into something growth so that it would grow and I could take out the first fruits every year and use it on something both I and my grandmother would appreciate. If it doesn't grow, I don't take anything out. If it grows extra, leave it in to compound.
LV