Norm-nudges are effective in encouraging sustainable consumer behaviour in various settings, by raising the salience of the target behaviour via social norms. Tourism presents a highly hedonic context, in which behaviour is primarily framed by self-oriented goals as opposed to normative ones related to the good of the environment and society. While the existing literature provides insights on the appropriate content of norm-nudges to raise the salience of normative goals, less is known about an appropriate frequency of nudges. It is important to address this gap in tourism because tourists need to be aware of desired sustainable behaviours, while overly obtrusive nudges may backfire. A field experiment was conducted to test the extent to which an increased frequency of norm-nudges has a backfiring effect on sustainable tourist behaviour, using donations for mountain-biking trails as the target behaviour. Results show that increasing the frequency of norm-nudges does not diminish their positive uptake, which suggests that they can be used more to encourage sustainable behaviour and enhance tourists’ experiences. Using actual and self-reported behavioural data, this study provides new empirical evidence on the effectiveness of increased frequency of norm-nudges in a real tourism setting, contributing to knowledge on norm-nudges and backfiring effects.