I guess making bigger transaction over higher quantity of smaller ones will be an option then to avoid fees and being more secured. But then I have another question - fee sometimes differs why is that ?
For example if you receive many dust transactions and collect over time large sum of BTC, when you try to send it, you will pay humongous fee just because number of the outputs of your transaction is so high.
Well, if you want to know more please read this short article: https://blog.blockchain.com/2016/12/15/bitcoin-transaction-fees-what-are-they-why-should-you-care/