I think they want to be especially cautious at Spa, given that this track is responsible for multiple deaths in recent years (Anthoine Hubert, Dilano van 't Hoff) and major injuries (Jack Aitken in GT3).

They definitely could try out more things in general though, like sending out the safety car to do reconnaissance laps on the conditions earlier. Apparently during the first lap before the start was aborted, a lot of drivers complained about visibility though so you can argue that they were trusting the drivers judgements.