Continuous Residence, Counting last year spent outside US?

I am a permanent resident since 6 years. The first 2 years I have been absent from the US and I got a reentry permit to come back, then lived in the US for 4 years. I have read in the citizenship guide that the last year - 1 day spent outside the US counts toward meeting the 5 yrs continuous residency requirement to file for citizenship. Is that true? Did anyone with such a case apply for citizenship and get approval from INS? Does the INS systematically take in account the last year spent outside the US as part of the 5 yrs continuous residency period, or are there special conditions for this year to be considered and what are these conditions? For example does the INS request proof like US tax filing, keeping residence and family ties in the US, etc. during the year spent outside the US.

Thanks

Yes, this is true and on other boards I have conversed with people who have used that clause.
The clause actually is in the immigration law (8CFR316.5(c)(1)(ii)):
"(ii) For period in excess of one (1) year. Unless an applicant applies for benefits in accordance with Sec. 316.5(d), absences from the United States for a continuous period of one (1) year or more during the period for which continuous residence is required under Sec. 316.2(a)(3) and (a)(5) shall disrupt the continuity of the applicant's residence. An applicant described in this paragraph who must satisfy a five-year statutory residence period may file an application for naturalization four years and one day following the date of the applicant's return to the United States to resume permanent residence."

Make sure, though, that you don't file even a day too early. People have reported that their cases got denied due to filing a couple days too early.
The "filing 90 days earlier" rule does not apply in the 4 year + 1 day case. Note that the law text above explicitly states "may file an application for naturalization four years and one day .."

Thanks very much for your answer and especially the notification that the 3 month advance filing does not apply in my case. What about keeping a home address or family ties in the US during the last year spent outside US. Do I need to proof that in my case?