Our pitch and gravel roof; again?

Thanks to those who previously commented on this topic for me several months ago. Since then.
I have contacted several roofing contractors about our built up pitch (tar) and gravel house roof which is not giving us any trouble at all. House single storey above ground bungalow, standing alone with 30 year old trees around it.
Roof is a simple 'shed' style without dormers 37 feet by 62 feet. Very easy to work on with eaves only eight feet above ground. Slope is about 3 feet in 17 feet. Not suitable for shingles. Weather can be rather severe, wet and windy, although not extremely cold or hot by North American standards. It's a salty maritime climate since we are about one kilometre from the North Atlantic.
Roof is 34 years old! The typical life for this type of roof is 25 years.
One contractor of unknown reputation did come and look at it and recommended total replacement with "Hot Roll Roofing" which I understand is a good system? for $8000.
I followed up on a second who apologised for not responding but has been "Too busy"; in his defence there is a lot of building going on but I am not hard to get hold of. haven't heard anything further! Probably cross them off the list? This second contractor without seeing the roof also recommended complete replacement, saying also that a cover-up job would only last a three to seven years and would be money wasted because complete replacement would then be needed.
I haven't heard back yet from the son of the original contractor. His late father did a good job back then. I've had a minimum of problems with the roof.
I also asked an ex colleague, now a leading local contractor of excellent reputation and social involvement whose brief comment was "If it isn't broke don't fix it"!
I can see a contractors viewpoint. They want to do a full and profitable job, probably preferring 'new' work and not have any problems with a patch up that may come back for further work and perhaps impair their reputation for good work. Also I agree if/when a leak occurs and if insulation gets wet it is/would be my real problem.
But I'm still not convinced that sweeping aside the pea gravel, applying another layer of tar and respreading the existing gravel and adding some more to compensate for what has been blown off over the 30+ years is not an option?
Because much older houses, often not as well built, some joined one to the other etc. as exist in the downtown of this old maritime, 99% wood frame residential construction city, with much flatter and with more complicated dormer roofs seem to exist? Commercial flat roofs btw do seem to be a problem here especially when snow is allowed to accumulate. and old barns and sheds (not exactly the same thing as a residential house of course) have been retarred in some cases for 100 years or until the barn rotted out and fell down.
At the indulgence of other posters I would welcome, again, any advice, comments, encouragement or discouragement regarding the above. Not worried about this coming winter but next year might be the time to make decision and in the meantime do my homework on available systems. The tongue and groove roof lumber on trusses is in good condition and well nailed. Attic ventilation is very good.
TIA Terry.
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At work we use an moisture meter on "flat" roofs to gauge when there is need for work on them. I have no experience in your area at all. I would continue to seek professional help locally for real answers. County agents might have some info, or maybe your insurance man.
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I somehow was elected to be overseer of an elderly neighbor & her home here on the west coast of Florida for 10+yrs as she aged and finally moved into and lived in a nursing home for a few yrs - she always hoped to move out of the nursing home and return home so she kept it forever ;). About one mile inland so not overly salty - but we sure do get rain. Tar and Gravel, about same pitch as yours - White Stones Roof was always a major concern to relatives/lawyers/real-estate-co(pre listed?) so I was forever appeasing them by calling roofers for inspections - none of which said replace it. There were occasional patches from rising nails which was always simply sweep away stones and go get a part bucket of hot tar and mesh - that'll be $200. It was over forty, less than 45 yrs old when the neighbor finally expired and then the family choose a roofer that did replace it whom told me it still had several yrs left, but if you want a new one - here's options & costs. Family went with a roll roofing `burn down stuff - looks cheezy but was least cost & agreeable between them. Home sold instantly,, thanks god !
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snip ............

Terry now adds; Many thanks to Sqlit and bumtracks, so far, for comments. BTW There are no lifting nails evident in this roof, only occasional very small areas where the felt looks a little bare of tar! Which is why I think another tar coating may be a good idea. Inside the roof space (it's so low up there, only crawling height, that you can't really call it an attic), no signs of leakage or even condensation. Terry.
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