Yes, No need to touch .ini just to remove light leaks. Give attention to walls, roof and floor in 3D application where you model them, properly unwrap the models with good padding between UV islands, and give descent resolution to these to avoid light leaks. Test your scene on production quality starting with .7 value in Static Lighting Level scale, Indirect Bounces 50-100 (Your choice), Indirect Lighting quality 2-4(depends upon your hardware power) and Indirect Lighting Smoothness .85. These values are more then sufficient to test your scene for problems related to light leaks and geometry errors.
Then move towards the uncharted waters of Static Lighting Level Scale .15 or .25 values if you want to take your scene quality to next level. Here whatever Epic says, you need to tweak .ini file to get scene free from blotches and leaks. But that’s the extreme. You can get pretty good results without .ini file if you experiment with editor lightmass settings.
PS - I never used the reflector method(bounce cards) either, it’s impractical if you consider Exterior/Interior together.