For lagers my batch size is 13 gallons / two 6.5 gal acid carboys.
I start with 2 fresh packs (I won't buy lager yeast over 45 days old)
My LHBS usually has very UGLY dates on their lager yeast, so I buy from a larger volume dealer and have it shipped.
Experiment to find out who can get you the fresh yeast overnight with just ground shipping.
I make 3 step starters on two separate stir plates, at the same time, one flask per yeast pack, with/ 1/8 teaspoon nutrient & 5 drops of Fermcap for the 1 & 2 l. flask, 10 drops for the 3 l. at 65 F.
1 l. for 48 hr.
2 l. for 48 hr.
3 l. for 48 hr.
Then chill to settle, rack off or decant brew day, draw 1000 ml./ 3 l. flask off the boil pot and chill to pitching temp, add back to each of the 3 l. flask, and put on the stir plate to oxygenate and activate the yeast prior to pitching.
I don't rack off from one step to the next, too much diddling can lead to contamination in my opinion. I would rather just Star San my flasks.
The first step is about 900 ml, so when I move to the 2 l., I just prepare ~ 800 ml. of water with the full weight of DME for a 2 l. starter which would be 200 grams, boil 6 min.
So when you add the original 1 L. flask to the 2 L. flask, it wont over fill.
And you do the same when going from 2 - 3 l. taking into consideration of the volume ~ 800 ml. with 300 g. of DME.
I end up with at least 1/2 in. of yeast on the bottom of the 3 l. flask
Using Tasty's fermentation schedule, I have had blow outs, with very little activity after 6 days.
Yes it is time consuming, but as Nate said you need a lot of vigorous yeast to ferment lagers.
I would rather spend my money on the extra DME and watch it grow than buying more yeast.
(My LHBS has only one or two packs 95 % of the time) You also do not know how the yeast was handled temp wise!
It may well be dead in the pack when you pitch it! So I grow it to see what I got. I too have bought dead lager yeast.
I have a separate temp controlled fridge just for lagers, pils, and bocks.
Spending about a week with yeast prep is a grind, but it has a positive effect on what goes in your glass.
Gary