Stasis Field Theory

Stasis field kraata can trap a being for a long time if they are at a strong enough stage and it has been shown a stasis field rahkshi can trap somebody for a long time even when not present. So I am wondering why Makuta need to concentrate to maintain a stasis field while the rahkshi or kraata do not? I have this theory that the reason Teridax needed concentration when he trapped Matoro was he could not the stasis field work automatically like usual since Matoro would be trapped for too long for the plant to work. Would this explain why it only looks like they need to concentrate for the stasis field to be maintained in order to work when in truth they do not need to since Teridax could not let it last too long when he used it?