The slow cooking time for beef depends on the cut and weight, as well as the heat setting of the slow cooker. Typically:

• For a 1 to 1.5 kg (2 to 3 pounds) beef brisket or stewing beef, cook for about 4-5 hours on high or 8-9 hours on low.
• For 1.5 to 2 kg (3 to 4 pounds), cook for 5-6 hours on high or 9-10 hours on low.
• For a beef joint of around 1.5 kg, cook 4-5 hours on high or 6-8 hours on low (up to 9 hours for brisket).
• For cubes of chuck or shin beef, 4 hours on high or up to 8 hours on low.

Beef is typically cooked until it reaches tenderness and is easy to shred or slice. The internal temperature target is about 71°C (160°F) when slow-cooked. Cooking times can vary depending on slow cooker model and personal preferences for doneness.

In summary, generally slow cooking beef takes:

• High setting: 4 to 6 hours
• Low setting: 8 to 10 hours

For best results, the beef should be cooked until tender enough to be easily shredded or sliced depending on the dish.