There are two places Collection settings can be set. Either on the device or in the Field Maps desktop app, which then defines the settings for all users of the map (you have to overide it if you want to use your device settings instead). The setting is for either the distance or time between each point captured. If you want something very accurate set it to capture every 1 second. Another option is to enable GPS averaging which will enforce better data collection.
I've tested a Garmin Glo 2 Bluetooth GPS with Field Maps and have found them pretty good. They can be a pain to sync up and I've had an issue once where I couldn't get it to find a position at all, but it was in dense forest when first trying to connect it (once connected it worked fine). There's a list of tested devices here
