I recommend switching between naked eye, binos and spotter for eye strain relief. Having good quality glass does wonders for your ability to glass for long periods.
Do a naked eye scan and use the spotter to look at anything that looks interesting - a high grade approach. Then, use a grid approach and look over everything in your view, don't skip anything. This will go much faster with practice than it will initially. You will be amazed at what you see gridding it out that you miss otherwise.
