Is one who delays most of his obligatory prayers to perform them minutes before their time expires, out of laziness and missing what is better, sinful, or is his action merely disliked? And what is the ruling if he does that relying on the non-obligation of congregational prayer in the mosque?

It is permissible to delay the prayer until the end of its chosen time, but it is not permissible to delay it until a time that takes it out of its chosen time, except for an excuse. And whoever does that without an excuse is sinful. It is permissible to delay the Isha prayer until midnight according to one opinion, and until the first third of the night according to another opinion. The best is to perform it in congregation at the beginning of its time. It is not the practice of the righteous to seek out concessions and abandon recommended acts, but rather to hasten to prayer at the beginning of its time. We advise the questioner not to ask too many of these questions, as they may stem from whisperings (waswasa).