I assume this probably relates to IF trg in a single engine a/c. The majority of such a/c have single system IF fit, without any backup systems. It may not be a big deal to skip checks for sim IF, but it is extremely back practice. Flying actual IF in SE a/c can be fraught with difficulty and danger, and it is imperative that students are taught and disciplined in carrying out full and meaningful thorough pre-flight checks of both primary flight instruments and navaids. If it is not happening for you, seriously consider the quality and content of your course instruction.
Couldn't disagree with both Foxmoth and 10540 - practical and sensible contributions