Food for thought: I have sometimes given close friends (only close personal friends!) nontrivial gifts of ZEC, in the manner of, “Install a wallet that supports shielded, and give me your shielded address so that I can send you a few hundred bucks worth of starter ZEC in total privacy.” I believe in privacy, so I do not pry into my friends’ finances; I have no idea if they held it, dumped it, spent it, or bought more ZEC to add to it. None of my business.
Any which way, their newbie wallets were born fully-shielded.
Pause to reflect on that for a few moments; and keep it in mind, when reading the below.
This is entirely unneeded for fully-shielded transactions. (It is an issue at shielding/unshielding boundaries—although the issue there is more complicated than most people understand.)
Fully-shielded transactions have no anonymity set issues, in the sense that applies to CoinJoins or Monero mixins. A fully-shielded transaction only reveals: “Someone sent some money somewhere.” Excluding network-layer spying, timing correlation to data leaked by e.g. a compromised/malicious shopcart, etc., the Zcash blockchain itself reveals no information whatsoever that could be used to infer anything whatsoever about the source or destination of funds in a fully-shielded transaction.
It is for this reason that Jameson Lopp described Zerocoin for Bitcoin and the Zerocash altcoin concept as “Infinite Anonymity”, in this 2014 essay (onebox metadata are wrong), before Zcash existed:
Indeed, it is true: Zero knowledge equals infinite anonymity.
Those are my favourite numbers. 
It doesn’t help anything, and it has made money that I need currently inaccessible to me. Although I have an historically high pain tolerance for using Zcash, I must admit that this is “ruining the core experience” for me.
Please never create unnecessary fully-shielded transactions in a misguided attempt to help the network. It does not help anything. Zcash has no need for decoys or added “noise” within the shielded value pools. Fully-shielded ZEC does not need obfuscation.
(Adding noise at the shielding/unshielding boundaries could be helpful; but that would require a rigorous understanding of what threats you are trying to counteract, and of how your transactions monkey-wrench them. Please do not try it without that rigorous approach.)