Check if all-inclusive is worth it.
All-inclusive is worth it when the food, drink and activities you would genuinely have bought cost more than the premium over the room-only rate. The break-even figure is the useful output: it tells you the daily spend at which the two options are identical, so you can judge honestly whether your holiday habits clear that bar. The critical discipline is valuing only what you would actually have purchased. Counting three restaurant meals and six cocktails a day when you normally eat two meals and drink two beers inflates the case for all-inclusive, and paying a premium for entitlements you do not use is exactly how these packages profit.
Premium
Premium per night = all-inclusive rate - room-only rate
Net benefit
Net = (meals + drinks + activities you would buy) - premium; break-even = premium
Because it is a single number you can test against your own behaviour. If breaking even needs 140 a day of food and drink and you know you spend 80 on holiday, the answer is settled without further arithmetic — and it does not depend on trusting the resort's valuation of what it includes.
Overvaluing the inclusions. Resorts present a long list of entitlements, and it is easy to count all of them at menu prices. Only count what you would have paid for anyway. If you would not have bought six cocktails, they are worth nothing to you no matter what the bar charges.