Once solid communications have been established, callsigns noted and conversation becomes casual often those callsigns come out perhaps a bit too fast and hard to understand BUT remember they have already been noted by the individuals or the group and have become just a legal formality. Trying to establish communications is another matter entirely so usually the callsign is given first in plain English, then repeated twice phonetically. Eh, at least that's procedure as I learned it, your mileage may vary. (;->)
Oh there are exceptions to the rule we call "lids" who can't get anything right and then there are the DX dog piles where anything goes, chaos and confusion rule the day. As the saying goes, if I had a dollar for every DX station that never gives the callsign expecting everyone to know it I'd be a millionaire. If you think you have trouble understanding callsigns try asking the DX "I didn't catch your call, please repeat." and PRAY you can understand him IF he doesn't ignore you and go on to the next caller before you have a chance to legally sign off at the end of the exchange.
Being new you have barely scratched the surface and callsigns are the least of your troubles. Wait 'till you've been around the block a few times and you'll understand the meaning of the song by BTO.
You ain't seen nothin' yet
B-B-B-Baby, you just ain't seen nothin' yet
Here's something, here's something that you're never gonna forget
B-B-B-Baby, you just ain't seen nothin' yet
You need educated
YouTube - BTO - You Ain't Seen Nothing Yet