See the very first Secret Wars with the Beyonder. Galactus used the world ship (TAA 2) as an emergency energy source (he didn't have time to go look for a world). I have read this over the years and looking at numerous issues this is how Galactus is portrayed. In the Jonathan Hickman Fantastic Four series Galactus stated to Read Richards that he consumed 4 worlds in anticipation of what was to come (fighting mad Celestials). The opposite of this is in play as well. Under John Bryne Galactus actually shrank in height because he let his power dwindle way too low. (FF #243 I believe). This sort of explains Galactus' variation in height. The more he consumes the bigger he gets, Under Walt Simonson (FF #340) Galactus started consuming the entire universe and he had grown to such enormous proportions that people were tiny specs to him. Galactus was so big that Reed and his team didn't even see him. Galactus was near planet size and getting bigger.
Basically what I'm saying is Galactus normally shows one planet is sufficient to sate his hunger and bring him back to peak performance.
I have all of the issues you cited. Thanks so much good friend for bringing them to my attention, I'll dig them out and re-read those issues.
