Landing pages
It is so frustrating if you click on some paid search and you will get something unexpected. Your landing page must be general and it might be even their homepage as well. your landing pages must have some clear message through ads. The problem with making the unique landing pages for each search ad is really time-consuming. As it is time taking for creating the separate landing pages but this thing is really in your favor and is closely related as well.
Concluding Words
Create the relevant ads by using different provided extensions that hold directly to the ad groups as it is a good call to the action. You must make different segments of your ad groups in smaller ones. Last but not least create some generic landing pages for each of your ad groups.