Hi Gadget
The handwriting is all uniform as if it had been copied neatly from somewhere else.
I'd definately agree that seeing the orignal page is always a good idea. It was standard practice as far as I'm aware, for the session clerk to jot down the events of the week as they happened and then transfer this into the register at once, so that may be an explanation for the uniform handwriting of many of the entries.
However, it does not explain why in some cases it says that extract was called for or in others that they were married, as you have mentioned. I wonder if this may be explained by cases of some of the couples actually being married in that parish, and in others they have been married in another parish, only one of the parties having been from Kilmarnock parish, so although the banns were read there, the marriage did not take place there? Just guessing here, but there must be a reason for the differences.
Could it be, if the above is a likely scenario, that Kilmarnock parish "called for an extract" from the other parish so that they had some documentation that the couple had indeed married? But I'm guessing that this couple were both in the same parish from the entry "William McMillan Glencairn Square and Janet Mackie in Fulburn Lane" so that is maybe not holding water as a theory!
Best wishes
Lesley