As sailingfool stated ... thinner is better; but, with an 'indicator coat' of a contrasting color beneath the 'working coats'.
Thick build up will eventually, after a few years, 'ablate' under the newer coats and then lose adhesion at the hull surface, then release in the form of scabs and craters.
To prevent such 'build-up', I apply the newer coats, as 'smooth as possible' (with WEST roller and a large plastic polyethylene trowel, etc.) ... such yields less 'effective' surface area which (to me) translates to longer service life and less paint needed to be applied ... and faster sailing in the 'light wind' conditions, etc.
My method for recoating:
1. lightly sand to promote a flat surface for the poly trowel to 'ride'. The light sanding will produce the equivalent of teeny 'mesas'.. dont worry about minor valleys and dings, etc. between each teeny 'mesa', as working the trowel will fill them in later.
2. Apply a 'stripe' of new paint with a WEST SYSTEM roller - about 1-1/2± 'roller-widths' wide. Immediately/quickly, draw the trowel across the stripe at a quite low angle to fill-in the valleys between the flat topped mesas.
3. Leave a 'dry' space almost to the width of the first troweled and leveled stripe and repeat.
4. Clean the trowel when needed ... I simply 'spritz it' with thinner, then wipe, then spritz.
5. Let dry/cure.
6. Return the following day or so and paint/fill-in the areas between the stripes already laid down, etc. If the previously applied paint can be 'dimpled' with a thumbnail - wait a day or more until it takes some thumbnail pressure to create the 'dimple'.
For scabs and craters that do release from the hull, I rough sand where the missing paint 'was' to establish 'tooth' in the surface, mix in a bit of 'micro-balloons' (fairing filler) to a small amount of paint and build the crater back up to 'flat and level' using the poly trowel. This is done before re-coating as a thick application can take a long time to dry/cure.
I use MUCH less paint; what I do seems to last much longer (I long distance sail a lot and it may be sometimes 2 years until I can 'recoat').
Once you master the roll-and-tip-with-a-trowel technique you can produce a bottom that is almost as smooth as a baby's ass - faster, more easier driven boat, less heel, good for 'light winds', etc..
Also, with a smooth bottom, any slime that attaches is more easily released by 'sailing'.
Less slime equates to less barnacle and hard-growth attachment, even with such paints as Micron-Extra.
hope this helps.