The divorce alone will be a change for the kids, so their routine is going to change regardless of what their father does. What matters most is whether their father will live up to the obligations set by the court and why he's asking for joint custody. Is it because joint custody would mean lower or no child support? or because he genuinely wants to spend time with his kids? It's definitely something to bring up with the court and your lawyer. Make sure that anyone involved knows that it's not a matter of you not wanting him to see his kids, but that he isn't a "parent" as he should be and that you don't believe he has proven that he will actually live up to those obligations to his kids. The court may order to review the situation for a while and keep track of his visitation and the arrangements, but generally if you live close to each other, joint custody is very common.
Lawyers work very hard. Most lawyers don't have "cases" per se (or at least the type of cases you see on TV). The truth is, most lawyers never see the inside of a courtroom. Those jobs are reserved for a specific set of lawyers called "Litigators" or part of a "Litigation Team".
It is extremely difficult to litigate a case. Many lawyers will work 14-16 hours per day preparing to go to court for as long as it takes them to be ready. When you go into litigation, you don't only care about what you are doing, you need to care about what the opposing counsel is doing. So, in essence, you prepare and break down the case you are working on from both sides of the issue.
Being a lawyer is really hard work from a mental standpoint...you need to critically assess issues and present them in a way that will help your side win. And, if you lose, the person you are representing is usually standing to lose something important. In criminal law, it would be freedom. In business law, it would be money. In family law, it could be custody of your kids.
I guess that's a really long way of saying yes, lawyers work hard.
And closed circuit to YNOT, there is a reason things are called movies....because they are a fantasy version of the truth.