I use MultiBit HD and that seems to use a lot of different wallets for incoming and outcoming transactions. So, a collection of wallets.
I think that is a pretty cool feature.
use a lot wallet will multiply the fee would you spend .. and it was very detrimental to us ..
Yes, sorry. I messed up my wording. It is a collection of addresses, not a collection of wallets

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I don't think the fee for having a lot of wallets is very high because for me that is just only a very small portion of your earnings or amount that you are going to send to someone. But for storing my bitcoins I don't use multiple wallets because that is going to be a waste of time for me, so I am sticking to one bitcoin wallet only.