Just as sitting on a leather saddle or couch that is too slippery gives you a profound sense of instability, sitting on a leather saddle or couch that is not slippery enough gives you an uncomfortable, almost "stuck" feeling. Leather is expensive and durable --- there's no reason you should have to endure leather that's not completely comfortable. A lack of slipperiness comes from a dryness in the leather and is an easy problem to fix.
Scoop out a silver dollar-sized amount of leather gloss onto a lint-free soft cloth. Leather gloss is a product that performs the dual job of conditioning and moisturising leather at once.
Dab the leather gloss evenly around the leather item that needs to be more slippery. Rub the leather gloss thoroughly into the entire surface area of the product. Use more if necessary. For example, if you're working on a leather saddle, one silver-dollar sized amount is enough. If you're working on a leather sofa, you'll need at least four or five applications to properly cover the entire surface area.
Allow the leather gloss to penetrate into the leather item for 30 minutes. Buff using a fresh, soft, lint-free cloth. When you're done buffing the item, touch it with your hands; it should feel significantly softer and slipperier. You can repeat this entire process if you'd to like to enhance the slipperiness even more.