If you have one hypo, you are more at risk of more. Especially if your hypo was treated with glucagon. Because this tells the liver to release its glucose stores. Once you start eating again your body prioritises restocking the liver glucose stores. So food you eat won't raise blood sugar, it will be funnelled into the liver's glucose stores. Restocking takes time. After a hypo treated with glucagon you should eat some complex carbs, with a reduced bolus.
Why is your friend treating hypos with 7 sandwiches, 6 packets of crisps? These are complex carbohydrates that won't work quickly to raise blood sugar. He should be treating hypos with dextrose tablets, glucojuice, hypostop gel, lucozade, jelly babies, Coke, fruit juice. Once he takes on 15g of carbs (in these simple carb forms) he should wait 10-15 minutes and then test again. If blood sugar is under 4 he should repeat. If blood sugar is over 4 he should have a complex carb snack like a digestive biscuit or oat cakes and then consider having a complex carb meal with a reduced bolus.
If he is not currently taking any insulin and still having multiple severe hypos has he had type 1 diabetes confirmed? When was he diagnosed with type 1 diabetes? Has he had cpeptide and GAD testing? Has he had investigations for Addisons? This is an autoimmune disorder that kills your corticosteroid production, corticosteroids usually keep blood sugars up. Addisons in a honeymooning type 1 could cause the kind of severe hypos your friend is experiencing without insulin.