There are two problems with mech fights in sentai.
First, most of the time they feel useless since the monster returns for no reason and provides no additional/interesting challenge or threat. It's specially boring when the monster of the week is more of a cunning villain, a saboteur or similar and then his "climax" is becoming a brawler just because.
Second, a lot of them feel empty as heck since the episode is already ending and the fight NEEDS to happen, so they just pose a bit and them the heroes throw the finisher (maybe a a some shooting/punch before) and win. There is no conflict or struggle at all.
GoBus did it better but even then it would be a better show without the mech fights being tucked in every episode.
Show me more individual mechs doing something besides throwing CG lightning, being actually important to the heroes' job. Make it part of the fucking plot too, instead of a rushed bloat that doesn't even make the toys look cool.