Depends on how your tolerance for cold temperatures is and what kind of accommodation you choose.
Private rooms / Hotels usually have blankets and linens.
Some albergues have wool blankets, but not all. So if you're cold with your liner, you're cold.
For albergues I'd always bring a small and lightweight sleeping bag, but that's Personal choice, as I've been cold in july even with the lightweight sleeping bag.
Some albergues are not heated so it can get cold at night.
If you want to find out what works for you, try at home. Wear what you'd wear at night in the albergue, and then sleep like that in the liner, at around 10°C. If you're fine with that, you might be OK with only a liner.