A colleague of mine has written her thesis and requested me to read and correct its grammar. I have seen some sentences like
The maximum deviation of the concentration values were obtained in the growing season, especially in May, in July, in August and in September.
As you see there is one 'in' for each month. I think that one preposition would be enough for all:
The maximum deviation of the concentration values were obtained in the growing season, especially in May, July, August and September.
Which one is more suitable?