Should fasttrack be used without a specified interface?

Normally I specify “In-interface” for my forward rules. Should I leave that off for fasttrack - and possibly the “global” foward for established/related?

Following the Wiki, the initial configuration doesn’t mention any interface, and “fasttrack” all lan traffic:

https://wiki.mikrotik.com/index.php?title=Manual:IP/Fasttrack&redirect=no#Initial_configuration

But, It can depends of each situation.