So this is what I do to check that: Missing blocks? - #5 by cultiv
In short: on the Farm tab, you should see attempts about every 10 seconds, that means everything is pretty great (especially if it occasionally says 1/40 instead of 0/40… if you have exactly 40 plots - the number before the / is most important, the number after the slash is how many plots were checked). If you don’t see that… then it’s time to dig into the logs!