Amen. The part of the Mark 4 verse that I underlined was to show the concept of different phases of growth until the ear was fully ripe. The fruit can be seen/discerned, but the process itself is not visible as such.......I think that is what is meant by "he knoweth not how". We go through our trials etc but even we don't know how it is working in us. We may only see the results in hindsight later, but don't know exactly how the fruit was wrought.
Just my own rambling thoughts here, but I believe God will judge at least partly based on how well or whether the person (believer) was running their race with the time they had. As long as they are in the race (narrow path) and not backslidden or avoiding the altar through disobedience. Like a child growing, we wouldn't expect a two year old to walk as well as an adult running a marathon. Like children in school are "graded" according to their grade level, not against university level standards. But conversely if an able-bodied 40 year old, for example, is still living at their parent's house toddling and stumbling around in diapers, 38 years later, well.....that one is not likely to be rewarded I would think. Whether such a one is still even saved or not, I think we need to let God decide that, since He is the only one who knows all the ins and outs of any person's situation. But the danger of not growing is that they can more easily fall away....as Heb 6 seems to imply. And as we sadly seem to see that happening with the modern church in general.
Suffering is key to growth.....".it is through much tribulation that we enter the kingdom of heaven".....but who can even say why some suffer more than others, and others seem to sail along with fewer bumps in the road... I don't know. Whether that is just an element of chance or God's doing per se, or some of each, I dont' know.
I needed the reminder about suffering recently, reading something in a little book by Watchman Nee (Breaking of the Outer Man and the Release of the Spirit).....it was strengthening. I haven't tended to suffer well.....too much murmuring, complaining and struggling and wriggling against it instead of accepting it and submitting myself to God IN it.