There is nothing wrong with gerrymandering. It's not me saying it, it's Sandra Day O'Connor, whose words I'll be paraphrasing (from memory; maybe later I'll dig up the actual opinion).
You can gerrymander to make your party's representatives' seats more secure, or you can gerrymander to have more seats for your party. In the former case your overall majority will be smaller when you win all the elections you expect to win, while in the latter case your overall majority will be bigger, though in each district the popular vote majority will be smaller. Either way your party can lose badly in the event of a wave election, either because few seats need flipping (in the first case), or because popular preferences change enough to swamp your large majority of small majority districts (second case).
We've had one anomalous period of 62 years of no wave elections in the past 100 years in the U.S.: 1932-1994. Since then we've had these wave election years that flipped the House or greatly enhanced the majority party's majority: 1994, 2006, 2008, 2010. That's... quite a few wave elections. That's in spite of the democrats having had 62 years to gerrymander before 1994, and despite the mid-cycle gerrymandering of the 00s. We can expect more wave elections.
You can gerrymander to make your party's representatives' seats more secure, or you can gerrymander to have more seats for your party. In the former case your overall majority will be smaller when you win all the elections you expect to win, while in the latter case your overall majority will be bigger, though in each district the popular vote majority will be smaller. Either way your party can lose badly in the event of a wave election, either because few seats need flipping (in the first case), or because popular preferences change enough to swamp your large majority of small majority districts (second case).
We've had one anomalous period of 62 years of no wave elections in the past 100 years in the U.S.: 1932-1994. Since then we've had these wave election years that flipped the House or greatly enhanced the majority party's majority: 1994, 2006, 2008, 2010. That's... quite a few wave elections. That's in spite of the democrats having had 62 years to gerrymander before 1994, and despite the mid-cycle gerrymandering of the 00s. We can expect more wave elections.
Gerrymandering is self-limiting.