It all depends on the series (and Authors skill
)
I have discovered some really good series books from reading a
middle book found at a used bookstore or Public Library.
It was not a series when I started reading in Analog SF&F
(McCaffery, Herbert, Asaro, Bujold...)
The publisher never printed Book3 (I had the first 2) in paper
(poor sales, change of management)
I no longer buy books that are now written in the Authors original series
(There are exceptions: A
universe that was designed from the start to be
contributed to )