Being a person who utilizes concise, practical fuinjutsu (Eric knows this personally)
I have to agree with the peanut gallery and state it is indeed situational. Also, vote Tomi as your top Fuinjutsu user for free pizza! Overthrow Athos' claim of top fuinjutsu user!!!!
Most of it's speculation at best, hence fuinjutsu created needs a clear purpose 'Ie, It prevents a person from forming chakra'
Q. How does it do it?
A. 'It disrupts the balancing of the ratio between spiritual and physical energy'
Q. How is it applied?
A. 'A tag with the seal on it is placed on the victim'
Q. How is it broken conventionally?
A. 'The Victim takes the tag off their body
It's an oversimplified example, but with this system you get the idea. The steps of the fuinjutsu should be clearly put out so people can work with it in their role-play either being the caster or the target of such. If you're the target, try to be reasonable and not use claims of 'I know enough about seals so I broke out of it instantly' If you're the caster, please don't be so anal as to say 'You don't know anything so you can't break out of it'. Work with your 'victim', and help direct the flow of their attempt to break it, whether it be successful or not/be reasonable with it.
If the victim has already made a post about having a specific counter seal for a type of fuinjutsu, say in their bio, has actively been seen using it without appearing moddish, that can work. Ie, Tomi was afflicted by a Juinjutsu by Eric on his shadow. Eric's juinjutsu works via Yin based chakras, Tomi is in possession of a Yin Sealing Method style Fuinjutsu. Tomi is able to suppress Eric's juinjutsu by this mechanic, yada yada. Eric accepts that his juinjutsu isn't effectively working against Tomi, but still technically has it on Tomi's person as Tomi hasn't spent the time to study up on shadow based curse seals/doesn't have the knowledge to unless he were to go to a knowledgable Nara, yada yada. Eric removes the Juinjutsu in return for knowledge of the Yin Sealing Method.
There you have a seal of sorts countered by another seal which both players were able to agree upon and so forth.