Bitcoin Forum

like the question above sorry for too many questions just trying to understand it more

Um. What all wallets?

If you run a wallet and wait for it to sync, its not going to magically sync any other wallet, no. Each wallet has to be run until it finish syncing.

different coins like dogecoin if i synced it will my litecoin wallet be synced too

it's diffirent coins, so it's use diffirent system, if your bitcoin Q.T. wallet synced and you not running litecoin wallet so your litecoin never get synced. you must running your wallet if you want to get synced.

I think you're a bit confused:

if you have (for example) bitcoin, litecoin and dogecoin, each of these coins has its own blockchain.
You need to sync those 3 blockchains individually.

IF you want a second (independant) wallet of the same altcoins (for example, two dogcoin wallets... one for you and one for your wife on the same pc), you can close down your wallet after synchronisation and rename your wallet.dat to (for example) wallet1.dat. When opening the QT client, a new (blank) wallet.dat will be created BUT it will use the (already downloaded) blockchain. To switch back: close the qt client, rename wallet.dat to wallet2.dat and wallet1.dat to wallet.dat (the qt client always uses wallet.dat as default wallet... you can also start the client using a command line argument in which you specify which .dat to open, but i personally think renaming the wallet.dat is easyer)

This way, you can have tens of wallets from the same ALTcoin without the need to re-download the  blockchain to switch wallets (just rename the wallet.dat). This has nothing to do with synching the blockchains of different altcoins.

ok thank you for this valuable information

Just the wallet you synched - but you COULD copy that updated copy of the blockchain to a wallet on a different machine and bring IT pretty much up to date, if it's the same client for the same coin (and as I understand it the client doesn't have to be the same-OS version, just the same CLIENT version, AKA you could update a Bitcoin 11 wallet on a Windows machine then copy over the blockchain files to a LINUX machine running Bitcoin 11 to update that client).

I see in your opinion what is the size of this whole transaction from new coins to famous coins

This will help you: https://bitinfocharts.com/
But be warned: it's not only the size of the blockchain that can be a bottleneck... Each transaction needs to be verified, so on slow pc's, it might take a long time to sync the blockchains because of CPU/memory limitations

if you use an exchange as deposit site you don't need to sync anything because they take care of this...

Be carefull: exchanges might be hacked, run with your coins, limit your accounts, freeze your accounts.
Just my personal opinion: i never keep any coins on an exchange for more than a couple of hours...

This. I had 60k sat on Cryptsy...

No. You have to separately sync each wallet.