The best thing would be to read the "Guide to Naturalization".
http://www.uscis.gov/files/article/M-476.pdf
If you go into the US Citizenship forum, you'll find that sometimes, just coming back every 6 months for a short stay is not enough to prove to the Immigration Officer that you didn't abandon residency. It would cause more problems than if she joined you later once she is done with her naturalization.
Don't forget that she would have to maintain her physical residency and continuous residency requirements all the way up to the interview and not just at time of applying for naturalization.
In short, it is ultimately up to the Immigration Officer if he/she is okay with things. They have the final say so...but why take the risk and give them a chance to say no to completing the naturalization process?
This piece is probably what you'll be interested in but I would say, read the whole document.
Q: What if I was outside the United States between 6 and 12 months?
If you leave the United States for more than 6 months, but less than 1 year, you have broken or disrupted your continuous residence unless you can prove otherwise. Read the “Document Checklist” in the back pocket of this Guide to find out what information you must give to prove you did not break your
continuous residence.
Q: What if I was outside the United States for 1 year or longer?
In almost all cases, if you leave the United States for 1 year or more, you have disrupted your continuous residence. This is true even if you have a Re-entry Permit.
If you leave the country for 1 year or longer, you may be eligible to re-enter as a Permanent Resident if you have a Re-entry Permit. But none of the time you were in the United States before you left the country counts toward your time in continuous residence.
If you return within 2 years, some of your time out of the country does count. In fact, the last 364 days of your time out of the country (1 year minus 1 day) counts toward meeting your continuous residence requirement.
Good Luck!