Lease extension question

SoozyJ22

The flats in my block all have a share of the freehold with leases which started at 99 years back when they were built in 1988. I've had a note in my postbox from my neighbour who runs our residents' committe saying a few people are interested in extending their leases, and giving the approximate costs involved for each flat if we want to .

That's all fine, I can see that 76 year leases might cause problems for people wanting to sell, and the costs involved for legal fees look reasonable. The thing I'm unsure about is that the letter talks about extending the leases back to 99 years. From what I've read online you can add 90 years to an existing lease, so I'm not sure why he's only talking of going to 99. Given all we need to pay are the legal costs, I would think it would make sense to for a longer extension, to save the owners going through the same exercise again in 20-25 years and paying all the fees again.

Before I have a chat about this with my neighbour, I wanted to see if anyone knows of a reason why we might only want to go to 99 years rather than a longer extension.

Thanks for any help you can give.