This is correct and also important when pressure pouring from a pot is the speed the alloy comes out of the pot and how high the lead level is. If the stream is too fast it may give you a void in the base and if the pot is too full, it may squirt out past your connection between the mold and the spout. For large BPCR bullets, I always pressure pour with a homemade ladle that holds quite a lot of lead for more pressure and if shooting in competition with pistols I always pressure pour my pistol bullets from the bottom but for just typical shooting, I bottom pour without pressure but even then, temperature, which bullet size, alloy, bullet length, and what the mold is made of matters. After a while you can get to where you can decide what is necessary and make your changes as needed.