The low fan setting would be better for use when the fan is very close to you (i.e.. on a desk), for larger settings like in a tent you will likely need to have it on high. I used this fan on high for 3 nights (around 8-10 hours each night) and the amazon brand batteries were still going strong, so this doesn’t seem to be too much of a battery …

https://www.amazon.com/Odoland-Portable-Camping-Lantern-Ceiling/dp/B016HM7QRE