Echo modifiers not lasting as stated

Went through Forlorn streets followed by Desert Arena. Stopped proceeding any further at the time of writing this post.
New modifiers from Forlorn streets lasts for 2 echoes.
New modifiers from Desert Arena lasts for 3 echoes.

My current remaining modifiers:
2 echoes left of enemy modifiers.
1 echo left of player modifiers.

Assuming Desert Arena modifiers activates upon entering the echo, there should at least be 2 echoes left for player modifiers after completion of Desert Arena.
It doesn’t add up.