Can you save your game without using Saviour Schnapps?
Yes
First there are the aforementioned "Saviour Schnapps", these can be bought or crafted and you can manually save the game each time you use one. The save game option in the pause menu does the same as using the item in your inventory.
Second there are beds. There are many beds you can use for this and only an hour is needed. You can use your personal bed, you unlock more as the story progresses. There are camp spots out in the world you can find and can use as well. And the most common is the taverns and bath houses, these will cost you money but will be found in almost any town. Note that you can't use just any bed in a person's house though, you must have bought it for the time, such as a tavern, or own it.
Third there are auto-saves. These take place at set points in quests, typically on completion of the quest but also during major steps in larger quests.
And last there is another method of modding. There is a mod that allows you to manually save without a saviour schnapps being used, effectively allowing you to save infinitely. This is only possible on PC right now.
In addition to @Virusbomb's answer : since patch 1.5 (maybe earlier), the beds in which you can save are marked "Sleep and save" instead of just "Sleep".
Those "save beds" include all the ones marked as "Your bed" on your map, and have your inventory chest nearby (one exception) :
Free beds :
- Talmberg Castle (no inventory chest)
- Rattay Mill
- Pirkstein Castle in south Rattay (after completing a specific main quest)
Paid beds :
- Rattay Inn (east of the city)
- Inn in the Glade (west of Neuhof)
- Uzhitz Inn
- Talmberg Inn
- Ledetchko Inn
- Sasau Inn
Other beds allow you to sleep and save but are not marked on the map, and don't have you inventory chest either (one exception) :
- Pribislavitz Rathaus (in the "From the Ashes" DLC, after building the Extended Rathaus ; has an inventory chest)
- Pribislavitz Inn (in the "From the Ashes" DLC, after building the Inn)
- Sasau monastery sick house
- One dug-in house in Rovna, at a Y fork (where you meet a bandit in the prologue, when returning to Skalitz, IIRC)
- One dug-in house south of the Skalitz' mines plateau, just before crossing the river south
- ... and many others I can't recall right now (poachers' hideouts in the forests, camps, sometimes ruined buildings, barns, etc.). There are few places were there isn't a save bed nearby.
Also, the "Save & quit" option does NOT allow you to reload more than once (it works like "save -> resume -> delete save"). It's more of an "extended pause" to allow you to resume your game later, than a real save.