How do loyalty apps and coupons affect the cheapest weekly shop across grocery chains?

On a tight budget, what long-lasting pantry staples and snacks are smartest to buy at a warehouse club?

Are ready-to-eat/ready-to-heat deli meals, pasta salads, and pre-cut vegetables made daily, how long are they safe/fresh (including 3 days), and which stores are most consistent for deli freshness?

What are the best examples of grocery store loss leaders that reliably draw shoppers in?

Which grocery chains are most reliable for fresh produce later in the day/end of day (fewer wilted greens and spoilage), and what store type is best for berries that last longer?