Much easier to hit the beach at night, no one to hassle you, less distractions, and you pretty much have the whole beach to yourself. Coin locations can change on a daily basis, depending on the tides, weather and erosion. Any erosion may expose new finds, wheras the targets you were previously detecting may well have been moved to a different location, be deeper down, or even out into the surf. I wouldn't worry about other operators on the beach, they never get everything, and the beach is quite a large area to totally cover. Sometimes the lowest tides will conveniently occur at night, exposing low tidal flats that hold many of the heavier targets, so don't be afraid to grab your gear for a night hunt.
The only way to have a hope of figuring out what your beach is doing with respect to grading of targets, is to grid up several areas to see where they may be occuring, especially any low spots, cuts, or where a rocky or clay base has started to protrude through the sand. Often after stormy weather you will see clued up local operators quickly hit any cuts that have appeared in the beach. This is usually evident by filled in detector holes at the base of the cuts, where coins and jewellery have dropped out of the newly eroded sand. You simply have to be at the right place at the right time, hence why it is important, if possible, to visually check out your local beach on a daily basis.
Beaches tend to do a very good job at grading items from lightest to heaviest. If you are picking up smaller/lighter coins, try further towards the waterline to see if the larger/heavier coins start to appear, and even further down for heavier items again (thinking lead, silver gold). Some heavier items may still be found at the top end of the beach, all depends on when they were dropped, if they have fallen out of exposed sand banks, or whether there is a rocky/clay base under the sand to prevent them from being washed out any further. Whilst these are just general observations, sometimes good targets can appear anywhere on the beach, with no real reasoning behind that being the case (call it being lucky).
High tide periods can also be a pain if operating a single frequency VLF detector, as usually half the beach is soaked in salt water which will cause falsing, and greatly affect the depth performance of your detector. It may appear dry on the surface, though dig down a few inches and you will soon find that water will start to pool into the hole. This will only leave you with the top portion of the beach to detect with any sort of respectable depth penetration.