- Average flying time to get to India, if you don't need a connecting flight at the destination, is 18-22 hours each way depending on where you fly from, the route and layovers. Assuming the actual flight time is an optimistic 20 hours, let's add the 3 hours that it takes to head out to the airport/check-in/security/etc each way, and another 2 hours to clear immigration/customs/etc each way. So, the time to get to and from the vacation is 50 hours.
- When you fly half way around the world, it's hard not to get jet-lagged. Optimistically, you've got to account for at least a half day (a very optimistic assumption) wasted on both ends of the trip. So you have another 24 hours spent jet-lagged.
- A special perk of visiting India is the high probability that you'll fall ill. Over the years, I've noticed my immunity to the Indian environment (food, water, air, etc) fade. This is true for most people I know who have lived outside of India for > 5 years. During each trip, it's very likely that you'll catch a stomach flu, get food poisoning, a fever, or generally fall sick. If you're lucky, it takes a day of complete rest and another half day of extreme caution to get back on track. So that's another 36 hours of lost vacation right there.
- Packing for a trip back from India isn't like packing for a quick flight to San Diego. A good deal of your last day is usually spent planning to pack, and then packing, and then re-packing to make sure your bags are all within weight limits. For those who don't live in metro areas, there's the additional time of travelling to metro areas. So let's throw in another 6 hours for all this.
So the total penalty of a trip to India is, roughly, 116 hours (a little under 5 days). Regardless of how long your vacation is, you're likely to incur this penalty, give-or-take a few hours. Heck, I would consider a 5-day trip within the US, or even a quick 5-day trip to Mexico, to be a decent vacation in itself.
It's pretty amazing to think that for many, the penalty of a vacation to visit friends and family is a whole other vacation. It's no wonder that most people who go to India need/want at least 3 weeks for the vacation to be worth it, and even then they feel gypped (rightly so?).
This also puts into perspective things that you otherwise might not think about. How much would you pay to avoid a 6-hour layover in Amsterdam en-route to India? Would a business-class ticket be worth the time it helps you shave off with airport formalities, jet-lag and worrying about luggage limits?