We see a lot of variation in historical fire regimes in terms of the fire frequency and intensity. In some places, the fire history might show a fire frequency of every 1-5 years. In other landscapes, the natural fire regime might show fires occurring every 10-20 years. Longleaf pine ecosystems have the highest natural fire frequency. An important thing to remember with the fire scar research is that we can only use fire scars when fires are relatively low in intensity and the trees survive. Some forests in North America are meant to only burn at high severity very rarely (e.g., every century), but it’s much harder to use fire scars in these systems; only around the fire edges where some trees might have survived. If you’re interested in fire frequency in the US, check out the PC2FM model of predicted potential natural fire return intervals based on physical chemistry factors alone (https://oakfirescience.com/research-brief/predicting-fire-frequency-with-chemistry-and-climate/). It’s a fascinating model that uses only physical factors to predict how much fire our landscapes might sustain. This model doesn't even include anthropogenic ignitions, which we know are and have been truly significant in many landscapes!