I've no reason to believe that footballers are any different from any other group of employees. You'll have some who are prepared to go the whole hog, treat their body as a temple and practice beyond what is expected of them. Then there are the journeymen for whom it's just another job.
In my line of work, there are programmers who study all the hours, pay for their own training courses and stay on top of all the industry developments. Then you have the majority who come in at 9, do their best until 5 then go home and switch off.