ItsIt's always a cost-benefit analysis. WhatsWhat's the cost of the feature breaking to you? If the cost is high, then test well and thoroughly. If the cost is low, test lightly or not at all.
There's also the cost of time-to-market to consider. Maybe itsit's better for you to deliver a mostly working feature thenthan to be late delivering a completely working feature.
ItsIt's almost impossible to answer these questions in the general IMO.
I think itsit's more important to preserve the ability to test in the case that some feature turns out to be more important than you originally realized.