I've used nothing but fletch tape for the past 4 years. I won't willingly fletch with glue again. The tape is just too easy and too good. No telling who you heard such nonsense from, but I've shot tape fletched arrows in weather as cold as 10 degrees and dry, up to and including 118 degree weather with 80% humidity - even in soaking rain - and have had ZERO problems.

However, I have found that I get better adhesion when I let freshly fletched arrows sit overnight before using them.