Not necessarily; self-monitoring is possible since trademark databases are publicly accessible. Whether a service is worth the cost depends on the commercial value of the brand and how much time and consistency you can dedicate to manual monitoring.
The case for a service comes down to two things: reliability and scope. Manual monitoring requires regular, consistent searches to avoid missing a conflicting application within the opposition window. A service does this automatically and covers a broader range of channels (domain names, social media, marketplaces) that are impractical to monitor manually at any useful frequency.
Set up trademark monitoring with Trama to catch similar filings as soon as they appear.