FTP Test in the middle of training plan

Hi, does it make sense to test your FTP in the middle of a training plan? I have a slight feeling that my FTP might already be too low, because I never have the slightest difficulty of maintaining the power.

I usually see FTP improvements quite fast, when I resume a proper training structure, but I wondered if the training plans are maybe not “designed” for FTP-value changes during the course of a plan.

What do you think?