To the person who asked "what are you spending your credits on" - just an example here. (Not our plans, necessarily, but just wanted to show how it can go quickly).
Say, you're a family of 4 - two adults, two kids - staying for 5 nights, 6 days.
You start the week with:
20 TS credits
20 CS credits
20 snack credits
You check in early on Saturday, and hit the parks. For lunch you have CS. That's 4 off that list, leaving 16.
Dinner, you want to start the vacation off with your family's favorite HDD dinner show, so that's 8 credits from your TS bank - leaving 12.
Sunday, you use your snack credits for some pastries at the MS Bakery - Spending 4, that leaves 16. For lunch, you decide to hit a resort pool and eat at their CS cafeteria type place. That's 4 more CS - leaving 12. Dinner is at Wolfgang Puck Cafe, and you opt to pay OOP for the kids. That uses 2 more TS credits, leaving 10.
Monday you visit Animal Kingdom. You eat at Tusker House for breakfast and use another 4 CS credits (because the portions are small for breakfast and the kids insist on having Mickey Waffles). Then, later that afternoon the kids are hungry but it's hot. So you just get two rib/chicken combos from Flame Tree and share - 2 more CS credits gone. 6 CS credits left. Dinner is at Ohana, and you pay (just pretend here) 2 adult credits and OOP for the kids again. That leaves 8 TS.
Tuesday morning you have to do Chef Mickey's for breakfast. Another 2 TS credits, leaving 6TS. You're stuffed from breakfast and grab "snacks" for lunch - leaving 12 snacks. Dinner everyone is hungry once again, but you've used your TS for the day at Chef Mickey's, so you decide to go with a CS place. Cosmic Ray's - again, you share to conserve and the combos are big, so you use 2 adult credits and have 4 CS left.
Wednesday you get Kona Cafe early in the morning, since it's you last day and you cannot survive if you go home without having Tonga Toast in your diet one time, and pay for the kids OOP. 2 TS down. Lunch is Tangierine Cafe, where you can share - so you have 2 CS credits left. Dinner is Le Cellier - you pay adults with 2 TS Credits, and kids OOP, leaving 2 TS credits.
Thursday is your day to return home, but your flight is the last one out. You have to meet the ME bus by 6, so you know an early dinner is in order. You get counter service for breakfast - using the last two credits - at the ABC Commissary. You are starving from only having half of a mickey waffle for breakfast, and you all decide to eat Mama Melrose's at 11:00. You pay OOP for the kids. Your TS are gone.
Bear in mind there are still some snack credits and I assume you would have gotten some Mickey Bars or smoothies or goodness knows what else in the week.
oOo oOo oOo oOo oOo oOo oOo oOo oOo oOo oOo oOo
OR - try this scenario - using just the table service credits "ethically" and having just one signature dinner:
Saturday - check in early, CS for lunch (16 CS left)
Have your first Mickey Bar on Main Street USA X4 (16 Snack Credits left)
HDD for dinner X 8 credits (12 TS left)
Sunday - Bakery for breakfast (4 pastries/snacks - 12 left)
CS at Resort pool for lunch (12 CS left)
Kids want ice cream by the pool X4 snack credits (12 left)
Dinner at WPC X 4 credits (8TS left)
Monday - Early Entry, Tusker House breakfast X4 CS (4 CS left)
Flame Tree BBQ for lunch X 4 CS (4 CS left)
Hot day, at AK no less, you get smoothies while watching the jungle parade X4 (8 Snack credits left)
Dinner at Ohana X 4 TS credits (4TS left)
Tuesday - Chef Mickey's for breakfast X4 (0 TS left)
Snacks for lunch X4 (4 Snacks left)
Cosmic Ray's dinner X4 CS (0 CS left)
Dole Whip Floats on Main Street during SpectroMagic Parade X4 SCs (0 left)
Wednesday - you are out of all your credits and you have to pay OOP for all your meals. Even if you've skipped the HDD and did a regular 1 credit meal, you have 4 credits on this day for your entire day. If you shared a bigger lunch at CS places, you might have 2 of these to share, too. You are out of snacks as well, so you eat granola bars in the hotel room for breakfast.
Thursday, you take the last flight out, but you spend all day in the park. Again, by now you are certainly out of meals and you have to pay OOP for breakfast and lunch, and perhaps dinner at the airport.
Now - of course, it can be done, and I'm sure lots of people budget their TS and CS credits so that they have enough for the whole trip. This is just one scenario where you aren't necessarily eating signature meals but would still run out of meal options before your last day at the park.