Our roof on one of our properties was 12 years old and failing badly (25 or 30 year shingles - warranty issues). We had called out Jim on a small job on our home previously on the recommendation of another contractor we used and were happy with his work and price so had him quote for this project and decided to go with him.
We knew the roof was spongy but on the first day of work, after removing some of the shingles, Jim called as there was considerable rotten plywood (we ended up replacing about 90% of the wood). WE went down and inspected and you could see just how bad it was so we gave our go ahead to replace what needed done. Yes it added considerable to the price of the job which was over and above the price quoted above but I have the peace of mind knowing that the job is done correctly. This is not a review on the previous company but I cannot believe that some of the wood didn't need replaced then (as it was a 30+ year old home then and I was charged for some but there was no signs of it having been changed) but I think it is easier, and definitely quicker for the roofer to just cover up with new shingles and move on with to another job without replacing. Jim was willing to take the time to do the job properly