No Lexol for me. Been leatherworking since I was a kid, holster and saddle making, and a lot of repairs, many of which were checked leather caused by improper conditioning - often with lexol or neatsfoot COMPOUND. Tons of guys use Lexol because it's readily available on the shelf at tack and farm supply shops all over the country, but being widely available doesn't make it good. Frankly, it's widely available because it's NOT good. It has a reputation of being neatsfoot oil and lanolin, but such is NOT true. It's largely synthetic, which is why it's cheap and lasts so long, and why it's not great for leather.
I personally condition my holsters and those I build with boot creams, Doc Marten's is one of my favorites. Kiwi neutral another.
Veg tanned leathers - like those used in holsters NEED to be oiled. However, "oil" is a very generic term. Synthetic oils will chemically degrade the leather over time, and microcrystalline "oils" like Renaissance Wax will also degrade (abrade) the leather fibers as well. Natural oils are good as leather conditioners. I prefer thicker cream type oils (higher molecular weight) and fats to allow me to heat them into the leather, but ensure they stay put during normal use and don't weep.
The chemistry of leather is actually quite straight forward, unfortunately, the contents of most leather conditioners are aimed at 1) selling a cheap product at high volume, 2) making leather look pretty in the short term but at the expense of long term damage, or 3) selling on gimmick alone.
EDIT: Pure linseed oil (or veg oil, corn oil, sunflower seed oil, olive oil, lard, or other natural fats - WITHOUT SALT ADDED, or dyes) make fine leather conditioners. Some tend to darken leather more than others. I've found animal fats to darken leather the least, which are also the ones which tend to be cream at room temp instead of oil. Linseed and bee's wax mixed just thick enough to produce a non-flowing cream is another blend I have used with good success, with the right chemistry to preserve leather without damaging it long term.