Can I alternate between USB and Wall Adapter?

Ok so this is the deal. I have had all iPhones since the 3GS. Always I have just charged my iPhone through USB. I work at my desk so it's always been easy to plug up and charge. Now iPhone 5s battery is a little larger and sometimes when I'm down to about 35-40% it takes forever on the USB. Now if I'm about 80% I can usually work and charge. Now I know all about that USB charges slower and the wall is faster. My question is would the battery suffer from one day wall charge the next day USB? Or I get to work with low bat so I use my wall charger for an hour say to top off and then later on in the day I get home and go USB. Would it be bad for the battery to use those 2 on a alternating basis??

I remember once reading that car chargers were bad for cells because it's not the same type of electricity as the wall. Something about it not being constant like the wall and they way it charges. Is always freaked me out and I never used my wall adapter. I know I know it was dumb but now with the 5S big battery I'm thinking its time to bring out the big guns. Just want to make sure it's cool to switch back and forth between the two without putting extra strain on batt..

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