More rapid growth leads to longer spaces, and slower growth to shorter spaces. Growth can be affected by water, heat/sunlight, fertilizer, crowded roots, etc.
Generally, as the season winds down, temps cool off, days are shorter, you fertilize less, decrease water and plants head toward dormancy. Thus, the nodes are always shorter at the tips. Spring flushing, with increased watering, added fertilizer, warmer and longer days, generally leads to more rapid growth and longer spacing. if you have a sufficiently cool period after first flush, the plant will decrease growth, and shorten nodes. When temps re-warm, growth speeds up again. If you looked at my plants (before I took cuttings) last season, many stopped growing with a cool period in August, and then grew a new flush of growth and fruit set afterwards. The plants looked like they had had two seasons, if you looked at the wood - but it was only one season with a hiatus in the middle.