I have BTC put aside in paper wallets for savings (even if I wanted to use them, taking them out of the paper is a hassle
).
On top of that, every once in a while I take all the paper money (or as I like to call it, monopoly money) change that I have in my wallet, convert them for BTC, and keep them on my phone. That way I always have some small change in BTC ready to spend. Between friends we settle small debts in BTC, buy eachother beer for BTC, etc. so I always have use for this pocket change.
tl;dr - If you want to have savings, put in savings. If you want to have spendable change, put in your phone. These do not contradict.