But I mean its not about at acreage or experience, its about land quality. My grandparents were experienced but had much less yield due to less water, rocky ground, etc. There is no one exact number and you need to prepare for the worst not the best.
Soil composition and nutrition levels, irrigation (or lack of it), insects and other scavengers, diseases, amount of sunlight during your growing season, temperature vairations...there are a ton of variables before you start considering the individual's knowledege, experience and techniques.