Adding yeast to bottling bucket?

Is there a rule of thumb as to if you should or shouldn’t add yeast to the bottling bucket?
I brewed my first pair of higher abv/longer fermentation ales. Winter warmer for Christmas and Smashing Pumpkin for Thanksgiving. Bottling SP this weekend and WW 10/30/2011 if ready. I have never had a batch not carbonate, some actually slightly over, and would like to make sure they will finish by each holiday. Thank you

I only add bottling yeast to big beers that have gone through an extended secondary (2-3 months).
Not needed for the SP. Probably not needed for the WW either but not going to hurt a thing to add it.

When did you brew them and when did they finish primary? The amount of time between that and when you bottle may determine if you should actually add yeast.

I just bottled some Imperial Stout that was about 8-10 weeks from brew date and am trying it without added yeast. Hoping I don’t have a problem

Fermentation will be 12 days primary 16 days secondary for the SP. SP OG with PM of 3 roasted pumpkins and 3lbs. of 6-row was 1.070 currently 1.018. ABV Approx. 7%. The WW went 2 weeks primary and will be in secondary for 4 weeks minimium and I would like to get it bottle conditioning by 10/30/11 so it can mellow out a bit by Christmas. Initial OG was 1.078 now at 1.020. My calculations give me an ABV of around 7.3%.

Always add a little rehydrated dry yeast to the bottling bucket, 1-2 grams is enough for a regular beer and a bit more for big beers, and gently stir the beer a couple times during the process to keep the sugar well-mixed, and you won’t have any problems with under- or over-carbonated beers (assuming you use the correct amount of sugar).

When I was bottling, it was standard to add yeast. Not always needed, but good insurance.