It is interesting the way church/hymn music is written. They are written with all combinations of sharps and flats including up to 5 flats, and 4 sharps. There are a lot of church songs written with five flats and five flats is very easy to play. Many church songs are written with 3 and 4 sharps, and sharps have been more difficult for me to play simply because playing my trombone in high school I was more familiar with flats as that is what most high school music for brass is written in. I got used to playing sharps in the orchestra, as many orchestral pieces are written in sharps, and a lot of them. We had high school kids come play with us who had never seen any sharps, that is the number of them that we played, and for a while they didn't know what to do with sharps because they were not familiar with them.
In some church song/hymn books we can encounter unusual keys. The book I am now playing out of is a wonderful old Hymnbook that Doug Oldham's Father worked on and was one of the contributors. He was a Baptist Evangelist, and they are wonderful people. Well anyway I found a song in that book, "Be Ready When He Comes" that is written with 6 flats! With the usually 5 the note C is also flat, which is the same as B natural, and while it is very easy to play 5 flats, that 6th flat, the note C can really throw you if you are not familiar with that key signature, and it takes you by surprise! I think once you get accustomed to playing music written in 6 flats it is easy. I also came across another church song/hymn, "Consecration," which is written in 5 sharps. I very seldom see 5 sharps in the music so it is more difficult for me. As well as the usualy 4 sharps the Note A is also sharp, which actually is B flat! I am sure if I were playing 5 sharps often that would be easy. There was a time that 3 sharps was a challenge, and now 4 sharps is pretty easy, but I seldom see 5 sharps and 6 flats, but then it is important to be able to play those key signatures well also!