Does Willer Express arrive late?

I am planning to visit some places in Japan on next August by bus mainly for economical reason. As I searched on the internet I found that the shinkansen trains in Japan are very rarely late. Can I assume the same for the willer bus?

For example, in their website there is a bus from Kobe to Chiba which is supposed to arrive at disneyland on 0720. Can I safely assume that, I will reach there before 0800?

As with most transport in Japan, buses are usually reliable. However, there could always be issues with traffic - weather conditions could be bad, there could be roadworks or a traffic accident blocking the road, etc. Reliable excluding extreme circumstances!

Overnight buses can be expected to arrive on time since there's much less traffic at night.