When you enter someone's encounter you'll skip current turn session and start only next one.
So, for example there're 5 guys with 20, 18, 16, 14 and 12 sequences, and you have 18 sequence.
They are skipping turns, watching youtube and waiting till someone enter enc.
Turn #1:
1) 20 sequence guy skipped turn.
2) you enter encounter. You'll have your turn on 2nd turn, because it'll be after current one.
3) 18 sequence guy shooting you.
4) 16 sequence guy shooting you.
5) 14 sequence guy still watching youtube.
6) 12 sequence guy afk.
Turn #2:
1) 20 sequence guy shooting you.
2) 18 sequence guy or you (because you have 18 too) has his turn.
etc.