Likes been make sure he's empty first with a 1/2 hour free run better still an hour,
Then start slow and build up,But keep your eye on him tho, But in my imho it will get him fitter, But the sharpness wont be there because like you say you dont get out that often cause of work, Only way he's going to get sharp is running rabbits,
But yip it will build a good baseline fittness, Iv tryed mine on them and i didnt get on with them really much simpler for me just to jump on the bike with my 3 and do quick hour its surpriseing how far you can bike in an hour, Plus added things like f