You don't need large spreads if you back count. Going higher than 1-4 doesn't add very much at all to your edge.
In a 5/6 S17 DAS BC 1-4 game, the SCORE without any indices is 38.15. Adding insurance is an additional 8.65 in SCORE, for a 22.6% gain. No insurance is VERY costly. And, the deeper you deal, the MORE costly it gets.