Buzz won't wee in the field and is currently living out and only coming in for a few hours whilst I ride them both and to chill, have a small feed. Him being an older gent I'm worried that not weeing for a long period of time will do him harm.
I trained my mare to wee on command in the first week I had her, simply to save on bedding, but it turned out to be a useful trick as I discovered that she wouldn't wee unless in the field, or in her stable. One time I hacked out for 4 hours and the poor creature crossed her legs until she was literally in sight of her stable then couldn't wait a second longer and let rip all over the yard. The look of displeasure on her face was very obvious. Ten minutes later and now back in her stable she did another huge one. I used to hack to and from shows and be out for the entire day, 8am to 7pm quite often, so like a little child, I used to command her to wee before we set off, and would offer her a visit to the long grass in one corner of the showground at lunchtime for the chance to have another if she wanted and about 75% of the time she did. But at least I knew she was comfortable before we set out!! Sometimes if I was mucking out fully on Saturdays and she would be tied up outside with a haynet, she would ask to go back into her stable to wee, by giving me the Princess Diana look and pathetically begging with a front leg. Miss my silly old girl.