That's a good question with a lot of different opinions on the best answer. About 50 draws is considered good by many for a 649 lotto and this may because each number is expected to show itself approximately every 25 draws so if a number does not appear it is cold
For most wheeling systems I've used, they don't need all the past draws.
They would use, say, the last 1 to 200 draws. Most give a choice of how many to use. The more draws you use, the longer it takes for the program to finish.
Thats depends a lot...some long time past trends can comeback and repeat partially ....its often the case....and if you look at the intervals from pairs or triples or LDs some can wait a very long time before coming right back at your doorstep....I'll say you need both latest draws and long time goner draws...
Hope this helps!