Answer: Theoretically, yes they would all come up at the same time. However, gladiola bulbs are usually dug and stored(remove the foliage first) in a cool, dry place for next year's planting. Left in the ground in most southern locations, most types will not naturalize and continue performing very well.
Staggered planting is a good way to lengthen the blooming period. However, those planted very late that have to attempt to bloom in very hot weather may not perform as well for you.
Thanks for the question!
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