Depending on the stakes, yes. It is categorically better than not voting at all. There is still the spoiler effect to consider, which may make voting third party a worse strategy in the complex, blind game that elections are. In elections where that isn’t as big of a risk, it’s a good way to indicate dissatisfaction with the status quo and the parties on offer. If there is a particularly convincing third party that many agree on, it also communicates what people do want. In presidential elections, in a country where the president already had so much power even before this whole shitshow, when one candidate is a much greater threat to the basic feasability of resistance, it’s a dangerous gamble, risking much for a fairly slim chance at an all-or-nothing victory. FPTP is one of the many things that are fucked up, but not every election has that kind of impact, and particularly if you’re in states where one party is so dominant that the spoiler effect is negligible anyways, it may be the more valuable choice.