Is it necessary to provide surge suppressor to every control relay?
If the control circuit power supply also powers electronic control equipment or if the relays are in the same enclosure with electronic control equipment, then every relay should have transient voltage suppression. For AC relay coils, RC suppression should be used. For DC coils, an anti-parallel diode should be used. If the soft starter is electronically controlled, that is electronic equipment in the same enclosure. Timing relays may also be electronic.