Rubber Roofing system – Lender & Insurer views?

I had EPDM (rubber roof) fitted on my own fully refurbed home 5 years ago – fitted to the flat roof parts – loft conversion and ground floor extension covering a very large percentage of the overall roof. Havent been any been any problems or issues with insurers. But on the ground floor area, the roof has been setup like a giant gutter capturing water from all around the rear of the house which then drains at one end. Lots of little patches where glued together to make a neat large drain exit to the normal downpipe so I guess EPDM is easy to mould around odd shaped fittings and I do slightly nervously keep an eye for leaks or glued bits coming undone but absolutely no problems so far.
Only one thing I would say and I wouldn’t have noticed it until we had a passing roofer who said EPDM is loosely fitted – its not stretched flat so you get little pools of water which quickly encourage green and licheny growth etc. making my 2 year old roof (as it was at the time) look like a 20 year old roof! I don’t see an issue with this.