One in a thousand women may not permit uninvited tickling even from a guy she would knock over her own mother to have. But the other 999 make and break their rules depending on how important the man in question is to them.
Okay, one thing: there are not so many guys women would knock over their own mother to have. 🙂 Most girls know that there will be a comparable or better guy waiting for them around the corner - who would most likely knock over more than just his mother to have THEM!
Second: They may go a little bit out of their way at the beginning of the relationship, but that may change very quickly once they got them hooked!