Depending upon where we live, & the local sheep population, shepherd imagery isn't necessarily helpful except when the principle comes close up & personal. How to make that happen? How to translate Jesus' Middle Eastern imagery still current in many parts of the world into our own local language in places where shepherding has moved on. Here in Oz, shepherding will most likely be done on horseback, in four wheel drives, on motor bikes, or even in helicopters. Only when the shepherd gets off or out & becomes personal to specific sheep does Jesus' imagery bite. A useful reminder that shepherding of the Jesus kind is always close up, personal, & hands on!
The / a good shepherd doesn't abandon sheep, singular or plural, because the going's become too hard. Pastor - ing is built on Jesus' promise & premise. That applies to preaching as pastoring, too. The relationship between Father (Source) & Son (not to mention Spirit!) is meant to flow onto & into us & all our relationships with each other. Not least in our dual roles as sheep & shepherds.
I appreciate the way Jesus 'explains' his job description at the end of this passage. There's no mention of any God-demanded sacrifice except the self-sacrifice that's the expression of total love. Total agape. Complete freedom to give & / or take up, take back life. The only 'charge' Jesus has received is to give & keep on giving. There is nothing sinister in this, compared with the way many conservatives still want to understand atonement in terms of the appeasement of an all demanding father figure. Let's neither preach such a figure, nor become one! That's not a figure recognizable in Jesus' teaching or actions.
A big hurdle we have to jump when we preach on this passage is the over-supply of 'cowboys' in many societies & an under-supply of shepherds!