Team CryptoInsightfull 
So I have an airgapped (using tails os on an old laptop) electrum (cold storage) wallet that I previously added additional receiving addresses by increasing the gap limit: wallet.change_gap_limit(110). I then copied those additional addresses to my connected (online) electrum watch-only wallet. I have used up enough of the additional receiving addresses that I went back into my airgapped wallet to generate another block of receiving addresses.
However, when I open my airgapped wallet, I don’t see the previous block of additional receiving addresses I generated; I only see the original 20 receiving addresses the wallet had when I created it.
So I did read this warning in the Electrum FAQ:
WARNING: Addresses beyond the gap limit will not automatically be recovered from the seed. To recover them will require either increasing the client’s gap limit or generating new addresses until the used addresses are found.
So I ran the same command I previously ran to increase the gap limit, expecting (hoping) to see previous addresses I generated, but the addresses added to the addresses tab in electrum are a different block of addresses, which I confirmed with: diff listPreviousAdds listOfNewAdds. Not one address from the previous block of generated addresses shows up in the new block of generated addresses.
So going by the warning message I pasted above from the Electrum wallet FAQ, how many new addresses might I need to generate to find the previous addresses I generated and have sent BTC to?
Update: Ok so I figured it out. I ended up mixing addresses from two different wallets, of which I have the seed for both, so ultimately all is well. Almost all of the addresses have been account for between the two accounts. I am still missing a couple that have been funded, but I think I just have to tweak the gap limit on one or both to find the remaining few.
It was never my intention to run two wallets, so now I need to decide whether to do so or consolidate and transfer the BTC in the wallet with the least amount to the other wallet and discard the second wallet. I wonder what benefits, if any, there could be in running two wallets?
I would still like to know if is there a better way to deal with adding and managing new receiving addresses using electrum, as this procedure seems a little hacky.
I do know from previous experience that if an online watching wallet has a corresponding cold storage wallet’s public key imported instead of just receiving addresses, that new addresses seem to get auto-populated as the existing address pool start to get used up. With security being my primary concern over convenience, I wonder which of these two methods of address generation, if either, could possibly be deemed less secure, for example, one might potentially present a larger attack surface.
Thks in advance.
