Doing a very limited amount of lifts to failure will produce better strength gains than doing no lifts to failure. However, when you do a heavy lift to failure it tends to create a psychological situation where you now expect failure at a given point, which is part of the reason that the WSB method never goes to failure in full range low rep bench, squat or deadlift. The 5-8 week rotation of max effort exercises also gives you enough time to get significantly stronger, so usually hitting a PR is doable, and often people will go for a second PR after the first...